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Today much attention is paid to the study of the pituitary ultrastructure of laboratory animals and humans. But there is not enough available literature to study the most important organ of internal secretion of productive animal. The aim of our work is to study the structure of the ultrastructure of cells of the anterior pituitary gland of cattle in the definitive period of postnatal ontogenesis. Histological, morphometric, and electron microscopic techniques were used to study the cellular composition of the anterior pituitary gland of cattle. It was revealed that the anterior lobe of the pituitary gland occupies 64 % of the entire pituitary parenchyma, while the posterior and middle lobes occupy 27% and 9%, respectively. After using general histological methods there are detected the functionally inactive chromophobes (41%) and chromophilic cells, which include acidophils (38%) and basophils (21%) in the anterior lobe of the pituitary gland. The electron microscopic studies in the parenchyma of the anterior pituitary gland let find Somatotropes that differ in the presence of a large number of secretory granules in the cytoplasm. Lactotropes are less common than somatotropes and differ from them in larger secretory granules. Corticotropes, gonadotropes and thyrotropes with a minimum content of secretory granules are the least detected. All identified endocrine cells are at different stages of functional activity.

Light and electron microscopic studies revealed ciliation of the epithelium of the entire gastro-intestinal tract of Polypterus. Acidophil cells were found in the different regions of the alimentary canal, including its derivatives (the lungs and hepato-pancreatic ducts). Compared to other primitive forms and modern teleosts, the extreme fusion of the intestinal caeca in Polypterus, the ciliation and the overall dispersion of acidophil cells may represent a special organization inherited from a palaeoniscoid ancestor. Attention is also drawn to a possible channel of early evolution and function of the stomach diverticulum.

The Hawaiian mongoose (Herpestes auropunctatus) is a seasonally breeding mammal whose pituitary gland resembles that of other Viverridae. Certain features, such as a prominent pars tuberalis interna and a double-layered pars intermedia forming a cup for the neurohypophysis, are unique. With the light microscope, five different cell types can be recognized in the pars distalis after staining with periodic acid-Schiff (PAS)-orange G. Two types of acidophils are seen, a small yellow-staining cell and a large angular orange cell. Two basophilic cells are also seen, one with fine PAS-positive cytoplasmic granules and the other with coarse PAS-positive granules in the cytoplasm. The last cell type seen is the chromophobe. Differential cell counts indicated an altered distribution of chromophils in the ventral pars distalis of the female mongoose with changing season and reproductive status, but the most striking change was a decreased percentage of basophils in the pars distalis during the nonbreeding season.

OBJECTIVE To determine the effects of prenatal administration of ethanol on cell count in pars distalis of pituitary gland in the rat pups. STUDY DESIGN Experimental study. PLACE AND DURATION OF STUDY Department of Anatomy, College of Physicians and Surgeons Pakistan, Regional Centre, Islamabad, Pakistan, from April 2014 to April 2015. METHODOLOGY Sixteen female rats (Sprague Dawley) were selected by random sampling method. Rats were mated and divided into control group A and experimental group B. From gestational day 10 to 18, mother rats received intraperitoneal injection of ethanol (Group B) and normal saline (Group A). Mother rats were allowed to complete their gestation and deliver spontaneously. When pups were born, only male pups were selected for the study. They were reared till day five. At 5ᵗʰ; day, pituitary glands were taken out and histological study was done in PAS-OG stain. Cell count was made in unit area (10,000 μ2) of pars distalis of pituitary gland. Student t-test was applied for analysing the data of cell counts in unit area. RESULTS Mean acidophil count was reduced in experimental group (70.19 ± 11.4) as compared to control group (92.65 ± 8.52, p

Twenty pituitary adenomas were studied using light microscopy, immunohistochemistry and electron microscopy. Based on clinical manifestations of hormonal hypersecretion they were divided into two groups, i.e. group-I (12 patients) with no endocrine dysfunction and group-II (8 patients) with endocrine dysfunction. Group-I could be further sub-divided into two groups based on IHC : group LA in which no hormone could be localised in the tissue (null cell adenomas) and group IB where hormones could be localised in the tissue (1). Tumours in group II, with light microscopy, were acidophil (n=5), basophil (n=1) or mixed (n=2) adenomas. Eight of these 20 cases were plurihormonal. Growth hormone, and prolactin were the commonest combination. This study has helped in the reclassification of the pituitary adenomas according to the hormone they produce.

The peripheral blood cells of a sisorid catfish Glyptosternum maculatum were studied using light microscope and transmission electron microscope. The size of cells and nucleus, and the percentage of different leucocytes were also described. Erythrocytes and four types of leucocytes: lymphocytes, heterophils, monocytes, and thrombocytes were characterized in G. maculatum blood. The dividing erythrocytes could be found sporadically. A plasma cell was observed under a transmission electron microscope. The morphology and structure of blood cells of G. maculatum were basically similar to those of other fish species, although there were also main differences, such as larger erythrocytes than other catfishes, absence of basophils and acidophils, and various types of thrombocytes (five types: lone nucleus, fusiform, tadpole-like, oval, and in a cluster).

The distribution of cell types in the pituitary gland was studied in a consecutive autopsy series of men over 40 years of age. Among 166 individuals, not previously subjected to prostatic surgery or oestrogen treatment, the proportion of PAS-positive cells was higher in men with hyperplasia or neoplasia of the prostate than among individuals showing a histologically normal prostate. PAS-positive cell counts were negatively influenced by several factors related to wasting disease, while acidophil cells apparently increased in conditions of acute and severe stress. Using multiple regression analysis, benign prostatic hyperplasia was selected as the only one among histological diagnoses which significantly reduced the variability of PAS-positive cell proportion, even when the negative influence of other factors had been accounted for. PAS-positive cell counts did not effectively discriminate between the various forms of abnormal prostatic growth encountered. The data presented indirectly give support to the concept of some form of endocrine derangement in the ageing male.

Transsphenoidal adenomectomy was done on 125 acromegalics. A clinicomorphological study was performed on 113 of these patients. The distribution of morphological types of tumors was similar in both sexes. In the total group it was: sparsely granulated GH cell adenomas 52.8%, densely granulated 25.7%, mixed somatotroph and lactotroph adenomas 15.9%, plurihormonal adenomas 1.8%, acidophil stem cell adenomas 2.6%, and oncocytoma 1.8%. The GH plasma level in male patients was significantly higher than in female patients. In both sexes GH secretion was highest in patients with mixed GH and PRL cell adenomas followed by patients with densely granulated GH cell adenomas. Plasma PRL levels were significantly elevated in all males, except for those with densely granulated GH adenomas where prolactinemia was normal. The mean plasma PRL levels were also elevated in females with highest values in mixed somatotroph and lactotroph adenomas. The PRL levels in female patients with densely granulated GH cell adenomas are more elevated than in female patients with sparsely granulated GH cell adenomas.

The present study aimed to evaluate the pharmacological effects of Menoprogen in the management of menopausal symptoms for aged female rats. Menoprogen was supplemented to a group of elderly female rats for 8 weeks. Subsequently, histopathological examinations were conducted in the isolated uterine and ovary tissues and pituitary glands of the rats. Serum levels of estradiol (E(2)), progesterone (P), follicle-stimulating hormone (FSH) and luteinizing hormone (LH) were determined. The ultrastructure of the rat ovarian granulocytes was analyzed. The histopathological examinations revealed no statistical difference in the quantity of follicles in the ovary and of acidophil and basophil cells in the anterior pituitary gland of the Menoprogen-fed rats versus healthy normal rats. Moreover, the cellular morphogenesis was in a healthy state for the Menoprogen-fed rats. Menoprogen significantly increased the levels of serum E(2) and P but reduced FSH and LH levels. The electron microscopic analysis showed that Menoprogen significantly retarded apoptosis of the ovarian granulocytes of the rats. Further investigation of Menoprogen for the alternative treatment of menopausal symptoms is warranted.

A 44-year-old Japanese man with elevated growth hormone levels and gradual deterioration of mental and renal function was admitted to the hospital. With his deteriorated general condition and renal failure, the patient developed pulmonary thromboembolism and died of respiratory failure. Autopsy examination was conducted, which revealed abnormal accumulation or intracytoplasmic storage of lipid-rich material in the small blood vessels, kidney, heart, and nervous system. After postmortem pathologic studies, including light-microscopic histochemistry, electron microscopy, and biochemical analysis of the stored lipid contents, a final diagnosis of Fabry disease was made. Histopathologic examination revealed a unique vasculopathy characterized by the presence of abnormal intracytoplasmic lipid inclusions and vascular remodeling. With regard to the clinical presentation of acromegaly, hyperplasia but not adenomatous transformation of the acidophils of the anterior pituitary gland with immunohistochemical detection of growth hormone within the cells was noted. In this case, the complication of acromegaly with hyperplasia of the acidophilic cells of the anterior pituitary gland and the unique vasculopathy causing significant organ failure, mainly of the kidney, heart, and central nervous systems, possibly as a result of microcirculatory failure, are considered to be not incidental findings but to be intimately involved in the pathogenesis of Farby disease.

A study was conducted to assess pathological changes in endocrine glands induced by 1 and 1.5 ppm dietary levels of aflatoxin (AF) in Athulya layer birds fed for 21 days. The control and AF fed layer birds did not show any clinical signs and mortality except for irregular areas of calcium deposits on egg shell surface. The histopathological alterations included basophil depletion and acidophil prominence in the pituitary and diffuse capsular thickening, hypercellularity of cortical areas and multiple cytoplasmic vacuolation of cortical cell in adrenal glands. The sections of thyroid gland showed pale and thinner colloid mass in the follicles and interfollicular congestion. The histopathological alterations in the present study could be attributed to indirect hepatotoxicity of AF.

From a dissertation read before the Society on January 22nd. 1969. Growth hormone (GH) is secreted by the acidophil cells of the anterior pituitary. It is a protein, partially α-helix in structure, of molecular weight 29,000 in man (1 ). In addition to its effect in promoting growth several metabolic effects follow its administration, one of which, the mobilisation of free fatty acid (FFA) from adipose tissue, will be discussed in some detail. The radio-immunoassay methods for estimating GH (2, 3) which are the most sensitive and accurate now available, depend on the fact that radio-iodinated GH of high specific activity (4) competes with standard or test GH in plasma for binding sites on a γ-globulin in antiserum prepared in rabbits. The competition results in ‘bound’ and ‘free’ 131I-GH which are separable electrophoretically and counted for radio-activity. Inhibition curves relating bound: free ratios to standards are drawn and test samples assayed against them. There is good evidence that the assay is specific (5). Reactive material is elevated in acromegaly and is absent after hypophysectomy: jugular vein plasma contains more than inferior vena cava plasma: cross-reaction occurs between plasma samples only from species whose pituitaries contain cross-reactive material: acromegalic plasma acts just as a plasma dilution of pituitary extract.

Orexins-A and -B are hypothalamic peptides derived from a precursor called prepro-orexin and relationated with the stimulation of food intake. They act on G protein receptors named orexin receptor 1 (OX(1)R) and orexin receptor 2 (OX(2)R), respectively. In the present study, we used RT-PCR and immunohistochemical techniques to detect the presence of OX(1)R and OX(2)R in human pituitary. A band of the expected size for both OX(1)R and OX(2)R was shown in human pituitary by RT-PCR. The cellular localization of OX(1)R and OX(2)R was carried out using histological techniques. By consecutive sections we demonstrated that OX(1)R was present in acidophil, diffusely distributed cells, which represent the half of the total adenohypophysis cell population. As was expected, these cells were shown to coexpress GH. OX(2)R was found in the pars intermedia and in clusters of basophil cells of the anterior pituitary, which coexpress ACTH. These results were confirmed by double immunofluorescence techniques. We also found focal positivity in axon terminals of neurohypophysis, more intense for OX(2)R than for OX(1)R. In conclusion, these results demonstrated for the first time that OX(1)R and OX(2)R were expressed by somatotrope and corticotrope cells, respectively.

Our purpose was to establish the earliest histologic parameters of acute hepatitis that correlated with recurrent hepatitis C virus (HCV) infection in liver allografts. Histologic reviews of posttransplant liver biopsies from eight patients with pretransplant chronic HCV (group I) and eight with pretransplant non-HCV liver disease (group II) were performed and correlated with concurrent or subsequent presence or absence of HCV-RNA by polymerase chain reaction (PCR). Six of eight group I patients developed HCV-RNA positivity in liver and serum. Of the histologic parameters studied, the presence of Kupffer cell hyperplasia, spotty hepatocellular necrosis (acidophil bodies), or both, correlated the most with the earliest diagnosis of acute recurrent hepatitis. The postoperative time period for the earliest diagnosis of recurrent HCV was variable (34 to 123 days). These early indicators and the time of their appearance were not predictive of the course of the disease process or the final outcome of the patient. The recurrence rate of HCV infection in liver allografts is high. The presence of Kupffer cell hyperplasia and diffusely scattered acidophil bodies are reliable, early histologic indicators of an acute hepatitic process.

Growth hormone(GH)-producing pituitary adenomas are morphologically heterogeneous and frequently contain not only GH immunoreactivity but also variable numbers of prolactin (PRL) immunopositive cells. Paraffin sections of 59 surgically removed GH- and/or PRL-producing adenomas classified by histology, immunocytochemistry (ICC) and electron microscopy were studied using in situ hybridization (ISH) for GH and PRL mRNA and combined with ICC for the coded hormones. Somatotroph adenomas (10 densely and 10 sparsely granulated tumours) and mammosomatotroph adenomas (10 cases) contained both GH mRNA and GH immunoreactivity. In 4 densely and 4 sparsely granulated somatotroph adenomas and 4 mammosomatotroph adenomas, only GH mRNA and its product were found. In 28 cases (6 densely and 6 sparsely granulated somatotroph adenomas, 10 mixed somatotroph-lactotroph adenomas and 6 mammosomatotroph adenomas) both GH and PRL mRNA were present, although no PRL immunoreactivity was not in 2 densely granulated somatotroph adenomas. In these cases, ISH for PRL mRNA combined with GH immunostaining revealed the presence of variable numbers of mammosomatotrophs. In 9 acidophil stem cell adenomas only PRL mRNA and its product were found; one tumour expressed both GH and PRL mRNA and their products. Nine lactotroph adenomas contained only PRL mRNA and PRL immunoreactivity. The results show that GH and/or PRL mRNA content could not be correlated with ICC for coded proteins and ultrastructural features. The mammosomatotrophs were more numerous using ISH when compared with ICC. Somatotroph, mammosomatotroph and mixed adenomas are closely related and they can be considered to represent one basic tumour type originating in a cell committed to GH production. This may undergo clonal differentiation towards a mammosomatotroph and further to the lactotroph line. The results also indicate that lactotroph adenomas arise in a cell committed to PRL production. Acidophil stem cell adenomas seem to be more closely related to lactotroph cells than somatotroph.

The peripheral blood cells of the gilthead seabream (Sparus aurata L.) were studied by light and transmission and scanning electron microscopic methods. Acidophilic erythroblasts and mature erythrocytes, round, oval, and fusiform thrombocytes, neutrophils, acidophils and basophils, lymphocytes, plasma cells, and monocyte-macrophages were characterized. A comparison of our light and electron microscopic results was carried out. The results were discussed with those for other fish species and the main modifications from the common vertebrate haematological pattern observed being considered.

This report describes a pituitary acidophil macroadenoma in a goat. Antemortem clinical findings included hypothermia and rumen stasis. Clinicopathologic findings included refractory hypoglycemia, low total thyroxin and insulin concentrations, elevated bile acid concentration, and hyposthenuria. In addition to the pituitary macroadenoma, bilateral atrophy of the zona reticularis of the adrenal glands was observed histologically.

Insulin-like growth factors(IGF) are involved in feedback regulation of growth hormone(GH) secretion from the pituitary. Though receptors for IGF-I and IGF-II have been identified on particulate preparations of rat pituitary, their localization and relationship to GH-secreting acidophils has not been determined. We used quantitative in vitro autoradiography and immunocytochemistry to simultaneously determine the distribution of IGF receptors and GH-secreting cells in human infant pituitary gland. Frozen or fixed post-mortem human infant pituitary glands were sectioned for binding studies, or immunocytochemistry. Binding for IGF-I and IGF-II showed characteristic specificity for respectively Type I and Type II receptors. Binding sites were visualized throughout the pituitary gland, with similar density and distribution for IGF-I and IGF-II receptor sites. Receptor density was two-fold higher in anterior than posterior pituitary, with highest density in the lateral horns of the anterior pituitary. The distribution of GH-containing cells (acidophils) was similar to IGF receptor distribution. Increased density of IGF receptors in regions of GH-secreting cells may point to the mechanism whereby IGF uniquely inhibits synthesis of human GH in contrast to its promotion of synthetic processes in other cells.

The progression from nonpregnancy through late lactation is associated with an increase in the proportion of anterior pituitary cells that secrete PRL and a comparable decrease in the percentage of cells that release GH. These fluctuations result from variations in both the number of cells that release GH or PRL alone and mammosomatotropes, cells that release both hormones concurrently. However, it has not been determined whether this reciprocal shift in PRL and GH secretors during the onset of lactation is readily reversible. In the present study, anterior pituitaries from adult virgin, late lactating, or postweaning female rats (4, 6, or 8 days) were dispersed with trypsin and subsequently assayed for PRL and GH release using reverse hemolytic plaque assays. We found that separating lactating females from their pups for only 4 days induced a reciprocal shift in the proportions of GH and PRL cells back to levels found in virgin females. Simultaneous plaque assays were then performed to determine whether this post-weaning shift in the percentages of GH and PRL secretors was due to changes in the abundance of cells that secrete each hormone alone or in the proportion of mammosomatotropes. The overall changes in GH and PRL cell proportions consisted of variations only in the fraction of cells that secreted either GH or PRL alone; no differences were observed in the percentage of mammosomatotropes or in the overall abundance of acidophils. Our results demonstrate that the reciprocal shifts in the proportions of PRL- and GH-secreting cells associated with lactation are rapidly reversible. Moreover, these results are consistent with our hypothesis that PRL and GH secretors are functionally interconvertible and further suggest that this process is bidirectional.

Estrogen (E2; estradiol) plays a key role in the regulation of many pituitary hormones. It exerts its effects by binding to the intracellular estrogen receptor (ER), which then functions as a transcription factor. Although E2 has been shown to regulate calbindin-D(9k) (CaBP-9k) in the female reproductive system of rodents, the effects of E2 on the regulation of CaBP-9k in male rats remain to be elucidated. To investigate E2-induced regulation of the pituitary CaBP-9k gene, immature male rats were injected with E2 daily for 3 consecutive days with a dose of 40 microg/kg body weight (BW). The expression levels of CaBP-9k mRNA and protein were analyzed by RT-PCR and Western blot analysis, respectively, in the absence and presence of ICI 182,780 (ICI), an E2 antagonist. In addition, the tissue localization of CaBP-9k was determined by immunohistochemistry. CaBP-9k was localized in the cytoplasm of a specific cell type (acidophils) in the anterior lobe of the pituitary gland and highly expressed in the intermediate lobe. Exposure to E2 increased the number of cells that stained positive for CaBP-9k. To determine which ER subtype is involved in CaBP-9k regulation in the pituitary, the immature rats were treated with propyl pyrazole triol (PPT, an ERalpha-selective ligand) or diarylpropionitrile (DPN, an ERbeta-selective ligand) for 3 days. Pituitary CaBP-9k expression was mainly mediated by PPT in immature male rats, whereas no significant alteration of pituitary CaBP-9k gene expression was observed after DPN treatment. In addition, the estrogenicity of PPT in the induction of CaBP-9k expression was completely blocked by an estrogen antagonist, ICI, indicating that pituitary CaBP-9k expression is solely induced by ERalpha. Taken together, these results suggest that pituitary CaBP-9k is induced by E2 in male rats and its expression is predominantly regulated by ERalpha, but not ERbeta.

Summary Pituitary glands of normal-termed stillborn goat kids with congenital goitre and normal-termed stillborn goat kids without congenital goitre were examined macroscopically, histopathologically and immunohistochemically. Thyroid glands of these animals were also examined grossly and microscopically. The pituitary glands of kids with goitre were larger than those of normal kids, and on histopathological examination there was hyperplasia of the acidophil cells in the ventral part of the glands. However, it was impossible to distinguish thyroid stimulating hormone (TSH)-secreting cells from other acidophil cells in sections stained with haematoxylin and eosin (HE). Red granules were observed in the cytoplasm of these hyperplastic cells in periodic acid-Schiff (PAS)-stained sections. Sections were also immunostained with an antibody against TSH using the streptavidin–biotin peroxidase technique. Immunohistochemistry revealed TSH-secreting cells to have increased in number in the pituitary glands of kids with congenital goitre because of the extensive proliferation when compared with those of normal kids. The present study indicated that the presence of multiple fetuses (twins or triplets) may be a predisposing factor for congenital goitre.

Activity of Carica papaya seeds extract on the pituitary, thyroid and parathyroid glands of rats were investigated. The ethanolic extract of C. papaya seeds (50 and 200 mg/kg) was administered orally daily to sexually mature male wistar rats for one and eight weeks. Histology of pituitary and thyroids were prepared. The thyrotrophs (TSH cells) of anterior pituitary showed progressive hypertrophy and degranulation at high dose levels of 200 mg/kg for one and eight weeks respectively. Acidophils somatotrophs (STH cells) and Lactotrophs or prolactin cells (LTH/PRL cells) showed no significant changes in both the experimental groups as compared to control. However, the thyroid glands of rats that were treated with 200 mg/kg extract showed pronounced hypertrophy, hyperplasia and degranulation with many empty follicles devoid of colloid. The parathyroid glands appeared normal. These observations showed possible side-effects of the C. papaya seeds in rats. KEY WORDS: Carica papaya , pituitary, thyroid, prarthyroid, wistar rats. Global Jnl Pure and Applied Sciences Vol.10(4) 2004: 515-517

Insulin-like growth factors (IGFs) have been reported to promote cell proliferation in many tumours, but their contribution to pituitary adenoma development and growth has not been characterized. We report the presence of insulin-like growth factor II (IGF-II) mRNA in pituitary adenomas using in situ hybridization (ISH). The intensity of IGF-II hybridization signal was correlated with adenoma type, and the presence of Ki-67. Among the 109 adenomas examined, 55 (50.4%) were positive for IGF-II mRNA. All acidophil stem cell, functioning corticotrophic and plurihormonal adenomas contained the message; a high incidence of signal was found among sparsely (7/8) and densely (4/6) granulated growth hormone (GH) cell adenomas, mixed GH cell-prolactin (PRL) cell adenomas (6/7), thyrotrophic (4/6) and null-cell (6/7) adenomas. Less frequently, IGF-II mRNA was localized in mammosomatotrophic, silent subtype 3, gonadotrophic, and oncocytic adenomas, whereas all sparsely granulated PRL cell adenomas and silent corticotrophic adenomas of subtypes 1 and 2 were negative. The MIB-I labelling index was significantly higher in adenomas with a moderate to intense IGF-II signal than in adenomas with weak or no signal. The results suggest that IGF-II, when highly expressed, may have a role in pituitary adenoma proliferation.

Interleukin-1 alpha (IL-1 alpha) and IL-1 beta bind to either the p80 type I IL-1 receptor (IL-1RI) or the p68 type II IL-1R (IL-1RII) on both T and B lymphocytes. We and others have previously shown that the anterior pituitary gland also has specific high affinity binding sites for IL-1 alpha (Kd = approximately 1 nM) and expresses transcripts for both isoforms of the IL-1R. However, the identity of cells in the anterior pituitary gland that express the IL-1R and whether different populations of adenohypophyseal cells express different isoforms of the IL-1R remain unknown. Here we have used a combination of immunohistochemistry and histochemistry to localize IL-1RI and IL-1RII to specific target cells in the mouse anterior pituitary gland. Perfusion-fixed, paraffin-embedded sections of anterior pituitary gland were immunolabeled with well characterized monoclonal antibodies to either IL-1RI or IL-1RII and counterstained using a modified Gomori's method to document acidophils and basophils. Immunolabeling demonstrated that both IL-1RI and IL-1RII were abundantly expressed on a single population of anterior pituitary gland cells and that these cells could be classified on the basis of histochemical staining as a subpopulation of acidophils. The distribution, morphology, and proportion of cells immunolabeled for IL-1RI and IL-1RII were consistent with GH-synthesizing cells. To confirm this hypothesis, a modified indirect avidin-biotin complex, sequential peroxidase/alkaline phosphatase technique was used to label anterior pituitary gland cells with antibodies to IL-1RI followed by antibodies to IL-1RII, GH, PRL, or ACTH. The IL-1RI-positive cells predominately coexpressed IL-1RII and GH, but very little, if any, PRL or ACTH. These data establish that the predominant cell population in the murine anterior pituitary gland that constitutively expresses IL-1R stain as acidophils histochemically, is round to oval with dense granular cytoplasm and eccentric nuclei, synthesizes GH, and simultaneously expresses IL-1RI and IL-1RII isoforms.

A classification of pituitary adenomas basing on detailed structural and immunohistochemical studies is accepted world-wide and is mandatory for each pathologist. Monohormonal (densely or sparsely granulated GH cell adenomas, Prolactin cell adenomas, ACTH cell adenomas, FSH/LH cell adenomas, alpha-subunit-only adenomas), bihormonal (mixed GH/Prolactin cell adenomas, mammosomatotroph cell adenomas, acidophil stem cell adenomas), plurihormonal (GH/Prolactin/Glycoprotein-positive adenomas, other Glycoprotein-positive types) and hormone-negative adenomas (null cell adenomas, oncocytic adenomas) have to be differentiated.

Age-related changes in the numbers of mammotrophs, somatotrophs, mammosomatotrophs, and the cells of other types in the anterior pituitary of female Wistar rat were measured by flow cytometry. The mammotrophs increased with age, and the somatotrophs decreased with senescence. The mammosomatotrophs increased remarkably in senescent rats, and these cells of the rats older than 21 months were about 10 times more than those of 3, and 12-13 months old rats. This result indicates that the stability of gene expression in cell differentiation is reduced in the aging process of the anterior pituitary.

Estrogen receptor (ER) was demonstrated in nontumorous and adenomatous human pituitaries by autoradiography and biochemical assays. In the present study, we investigated ER mRNA by in situ hybridization applied on paraffin section of 9 nontumorous pituitaries obtained at surgery or autopsy and 109 surgically removed adenomas. In nontumorous pituitaries, in situ hybridization combined with immunocytochemistry revealed hybridization signal in GH-, PRL-, ACTH-, TSH-, and LH/FSH-immunoreactive cells, with the highest intensity in PRL-immunoreactive cells. ER mRNA was also localized in Crooke's cells, corticotrophs extending to posterior lobe, cells lining the pars intermedia cavities, and squamous nests of pars tuberalis. The neurohypophysis, endothelium, and connective tissue expressed no ER gene. ER mRNA was present in all adenoma types, including somatotroph, lactotroph, mixed somatotroph-lactotroph, mammosomatotroph, acidophil stem cell, functioning and silent corticotroph, thyrotroph, gonadotroph, null cell adenomas, and oncocytomas. The strongest signal was seen in some lactotroph and mammosomatotroph adenomas. In 9 lactotroph adenomas exposed to bromocriptine (long-acting repeatable injectable form), the hybridization signal was weak or absent, suggesting that suppression of ER gene plays a role in the inhibition of PRL synthesis and tumor growth.

I. Introduction MORE than a half century has passed since Romeis first proposed the “one cell-one hormone” theory which holds that each of the major pituitary hormones is produced by a separate and distinct cell type (1). Consistent with this idea, the acidophilic staining cells (termed acidophils) of the adenohypophysis have been traditionally subdivided into two categories, those that secrete only GH and others that produce just PRL. This view was supported by considerable tinctorial evidence available at the time of Romeis' hypothesis and generated in the subsequent three decades (1–5). Moreover, data produced throughout the 1970s and early 1980s by the use of light microscopic immunocytochemistry (ICC) and immunofluorescence were generally consonant with the one cell-one hormone theory, except in the case of certain pituitary tumors (6–8). The presence of bihormonal acidophils in this latter situation was attributed to aberrant mechanisms attendant to the neoplastic condition. However, as will be disc...

Estrogen (E2; estradiol) plays a key role in the regulation of many pituitary hormones. It exerts its effects by binding to the intracellular estrogen receptor (ER), which then functions as a transcription factor. Although E2 has been shown to regulate calbindin-D9k (CaBP-9k) in the female reproductive system of rodents, the effects of E2 on the regulation of CaBP-9k in male rats remains to be elucidated. For investigation of E2-induced regulation of the pituitary CaBP-9k gene, immature male rats were injected with E2 daily for three consecutive days with a dose of 40 µg kg–1 body weight (BW). The expression levels of CaBP-9k mRNA and protein were analyzed by RT-PCR and Western blot analysis, respectively, in the absence and presence of ICI 182 780 (ICI), an E2 antagonist. In addition, the tissue localization of CaBP-9k was determined by immunohistochemistry. CaBP-9k was localized in the cytoplasm of a specific cell type (acidophils) in the anterior lobe of the pituitary gland and highly expressed in the intermediate lobe. Exposure to E2 increased the number of cells that stained positive for CaBP-9k. For determination of which ER subtype is involved in CaBP-9k regulation in the pituitary, the immature rats were treated with 1 mg kg–1 BW propyl pyrazole triol (PPT, an ER-α-selective ligand) or diarylpropionitrile (DPN, an ER-β-selective ligand) for three days. The data were analyzed by the non-parametric procedure of the Kruskal-Wallis test, followed by Dunnett's test for two-pair comparisons. Pituitary CaBP-9k expression was mainly mediated by PPT in immature male rats, whereas no significant alteration of pituitary CaBP-9k gene expression was observed after DPN treatment. In addition, the estrogenicity of PPT in the induction of CaBP-9k expression was completely blocked by an estrogen antagonist, ICI 182 780, indicating that pituitary CaBP-9k expression is solely induced by ER-α. Taken together, these results suggest that pituitary CaBP-9k is induced by estrogen in male rats and its expression is predominantly regulated by ER-α, but not ER-β.

Fifty-three species have been formally described in Chone Krøyer, 1856, showing wide variation in the shapes of dorsal lips, peristomium, and posterior abdominal uncini. Previous studies indicate that such variation could result in splitting of the genus; however, the original description of the type species, C. infundibuliformis did not include critical details and illustrations, and for other species, incomplete or misleading information has been provided. In order to redescribe the species C. infundibuliformis and delineate the genus, type and topotype materials were reviewed, and histological sections of the appendages of the branchial crown, collar and glandular ridge are described. The redescription points out that in C. infundibuliformis: 1) insertion of the branchial lobes is not exposed beyond the collar; 2) radioles have a paired series of pinnules of different sizes; 3) radiolar flanges are broad; 4) dorsal lips are broadly rounded, as long as wide, without mid-rib; they have hyaline cartilage, but there is no extension of the branchial skeleton; 5) dorsal lips are vascularized by a plexus of small blood vessels derived from the basal branchial blood vessels, which further back communicate with the dorsal vessel; 6) thoracic uncini have teeth above the main fang of unequal size, median tooth of basal row larger than teeth in subsequent rows; 7) uncinus shape shows variation within each torus, but no intersegmental gradation is appreciable; 8) females with oocytes distributed in all thoracic and abdominal segments; males with sperm in abdomen, with barrel-shaped nucleus and mushroom-shaped acrosome. The collar is supported by a dense mass of hyaline cartilage and covered by glandular epithelium composed of basophile glands. Acidophil glands, tubular-shaped with granulose secretions, constitute the glandular ridge. Size of teeth in thoracic uncini, presence or absence of abdominal uncini variation, latero-ventral posterior abdominal depression, dorsal lips internal construction and glandular ridge are compared among some species of Chone and close genera.

The pro-adenohypophysis (pro-AH) of migrating adult river lamprey, Lampetra fluviatilis, has been examined from October, when the gonads are developing slowly, until May, when the sexual maturation is completed. Two granulated cell types are dominating. One is chromophobic (C2, 95 nm), the other is basophilic (B1-B3) and probably gonadotropic. The mean diameter of the basophil secretory granules increases from 150 nm in October to 220 nm in April and May. The staining affinity of a rare, granulated cell type (D, 115 nm) has not been established. No acidophil cells are found in the pro-AH. The ultrastructural characteristics of the lead hematoxylin positive cells found sometimes in paraffin sections are unknown. Non-glandular stellate cells are common. They contain microfilaments, are probably contractile, and transform to phagocytes during the last months before spawning. This phagocytosis involves only the basophil cells. It is suggested that the stellate cells in this way destroy excess hormone. All cell types in the pituitary accumulate large irregular lipid droplets during the last month before spawning. These lipid droplets seem to be expelled from residual bodies as an end product of autolysis and phagocytosis.

The pituitary gland of the ricefield eel, Monopterus albus is made up of the neurohypophysis, which form the central core, and the adenohypophysis, which completely surrounds the former except at the infundibular connection. Pituitaries, in longitudinal and transverse serial sections, lave been studied by standard histological and histochemical techniques including Periodic acid-Schiff(PAS)/Celestine blue (CB)/Orange Gy- (OG), Herlant's tetrachrome (HT), Lead haematoxylin (PbH)/PAS, Aldehyde Fuchsin (AF), Luxol fast blue (LFB)/PAS/OG, Alcian blue (AB, pH 0.2 and pH 3.0)/PAS/OG, and Aldehyde Thionine (AT)/PAS/LFB. Seven tinctorial cell types are distinguishable in the adenohypophysis: the erythrosiniphilic and PbH-positive amphiphil (Type 1); erythrosinophilic acidophil (Type 2); orangeophilic acidophil (Type 3) ; PbH-positive acidophil (Type 4) ; very intensively AF-positive, AB-positive and AT-positive basophil (Type 5) ; weakly AF-positive, AB-positive and AT-positive basophil (Type 6) ; strongly AF-positive, AB-positive and AT-positive (Type 7). Chromophobes which show no affinity for any of the above stains are also found. The neurohypophysis shows extensive interdigitations and staining with AF, AB and AT indicates that the neurosecretion is concentrated towards the distal end of the neurohypophysis. Blood capillaries are found in abundance both in the adenohypophysis and in the neurohypophysis. The present report is the first in the series of studies on the role of pituitary in natural sex reversal in Monopterus and provides the basic information on the pituitary cytology and structure for further experimental and biochemical investigations which are reported separately.

The complement fixation immunoassay (CFIA) was used for quantitating growth hormone (GH) in crude anterior pituitary extracts from rats subjected to thyroidectomy with or without cortisol and exogenous GH administration. The results obtained from this study were compared with pertinent bioassay (tibia test) results or correlated with the pituitary acidophil cell counts. Whereas it has been reported that pituitary GH levels are normal by the tibia test at 2 weeks after thyroidectomy, the highly specific CFIA method showed an actual 87 % decrement which correlated well with the reduction in acidophils. In addition, the apparently normal content of GH after cortisol administration to thyroidectomized rats, as measured by the tibia test, was contradictory to the very low acidophil population and to the marked reduction in pituitary GH content as measured by the CFIA. Furthermore, theoretical tibia responses illustrate the inconsistency of the bioassay in different experimental conditions. If, as previously suggested, the content of thyrotrophin (TSH) in the crude pituitary extracts renders the bioassay of GH a dubious procedure, then the superiority of immunoassay is obvious.

This review discusses the pathophysiology of acromegaly. Acromegaly has been classified in this paper into distinct entities based on etiology, ultrastructural features of the pituitary, and cytogenesis. This classification has been proposed based on clinical signs, immunoperoxidase techniques, transmission electromicroscopy and immunoelectron microscopy. Pituitary causes of acromegaly include densely granulated adenomas, sparsely granulated adenomas, mixed growth hormone and prolactin cell adenomas, acidophil stem cell adenomas, mammosomatotroph cell adenomas, and pleurihormonal adenomas. GH cell hyperplasia and GH cell carcinoma are also discussed. Extrapituitary causes of acromegaly include eutopic GH cell adenoma in the sphenoid sinus or parapharyngeal region and excess GHRF secretion which may be eutopic or ectopic. The pathological, clinical, and biochemical evidence in favor of a pituitary or hypothalamic etiology of acromegaly has been reviewed. Finally, a multistage theory of GH cell tumorigenesis has been proposed as a model in an attempt to unify the genetic, environmental and biochemical factors implicated in the pathogenesis of acromegaly.

Fine structural criteria for identifying thyroid-stimulating hormone (TSH) cells in immature and mature rats have been studied by a modified superimposition technique. On days 10 and 20, some small oval immature TSH cells are scattered individually throughout the glandular tissue with a peripheral immunoreactive rim resulting from the sparse distribution of minute secretory granules less than 50 nm in diameter. The immunostained stellate TSH cells are clustered and have secretory granules 50-100 nm in diameter at the cell margins. On day 60, a few small immature TSH cells still remain. Although a few polygonal TSH cells that may not fully mature accumulate secretory granules 100-150 nm in diameter at the cell margins, the majority of TSH cells take the form of large stellate cells filled with secretory granules with the corresponding diameter, and surround an acidophil. These stellate TSH cells are characterized by dense arrangement of parallel arrays of rough endoplasmic reticulum (rER) or rER cisternae. The clustered or isolated elongate TSH cells are also observed to be vesiculated and to have numerous secretory granules 150-250 nm in diameter. In addition, large oval vesiculated TSH cells storing numerous secretory granules 150-250 nm in diameter appear sporadically in the gland, ultrastructurally resembling the gonadotrophs. It is concluded that the rat TSH cell is not a single type with a particular ultrastructure, but modifies its morphology according to its maturation or functional phase.

Isolated pituitary cells from 14-day-old female, 14-day-old male, and adult male rats were separated into several fractions by unit gravity sedimentation. With preparations from 14-day-old animals, the percentage of basophils increased from top to bottom of the gradient. The bottom fractions contained large basophils with a purity attaining almost 90% in the female and 75% in the male preparation. The same fraction prepared from adult male rats was composed of over 80% of large acidophils. As identified by immunostaining, the majority of the female large basophils were gonadotrophs, whereas in 14-day-old males about 1/3 of these basophils were thyrotrophs. The relative proportion of medium and small sized gonadotrophs and of thyrotrophs was also higher in the 14-day-old rats than in the adults. An estimate of the distribution of FSH and LH among the gonadotrophs was made by comparing the number of cells reacting with anti-FSH, with anti-LH, and with a mixture of both antisera. The data suggested that irrespective of cell size, the majority of the gonadotrophs in 14-day-old rats contained both FSH and LH. In most fractions, the occurrence of cells with only one hormone was more apparent in the males than in the females. In adult rats, cells with only FSH were most abundant in the fraction with large gonadotrophs. The distribution of hormone content, as measured by RIA, was highly characteristic for each animal group. In 14-day-old females, more than 70% of the recovered hormones was in the large gonadotrophs. In 14-day-old and adult males, substantial amounts of hormone were also recovered from medium sized gonadotrophs. The present findings suggest a relationship between developmental changes in pituitary hormone secretion and changes in pituitary cell type distribution.

Mitotic rates of the six types of immunohistochemically identifiable adenohypophysial cells were histometrically calculated in colchicine-pretrated male rats 5, 17, 30 and 70 days old. Sections were stained with the antisera against rLH, rFSH, rTSH, oGH, rPRL and pACTH1–39. The mitotic growth rate of the anterior pituitary gland at 30 days of age was much higher than at other times. Mitotic growth rates of GH and PRL cells increased with advancing age, while those of ACTH-, TSH- and immunonegative cells decreased with advancing age. LH/FSH cells showed no variation in mitotic growth rate with age. Mitotic cells can be classified into six cell types based on their fine structural properties: (1) agranular cells associated with the folliculo-stellate cells; (2) ambiguous cells with scanty minute secretory granules (50–150 nm in diameter); (3) basophils with a number of small secretory granules (130–200 nm); (4) immature acidophils whose large secretory granules (130–300 nm) are sporadically scattered; (5) acidophils with numerous spherical larger secretory granules (200–300 nm); and (6) prolactin cells with large polymorphic granules. At day 5 there was a high mitotic rate of the agranular and ambiguous cells [types (1) and (2)]; at day 70 a high mitotic rate was found in immature and mature acidophils [types (4) and (5)]. The mitotic rate of basophils (type 3) was high only at day 17 and low at all other times. The mitotic rate of prolactin cells (type 6) showed a slight increment with advancing age. It is concluded that the mitotic rates of the six cell types are age-dependent.

Development of acidophils was investigated electron microscopically in pituitaries from the rat embryos on the 15th, 17th, 18th and 20th day of gestation and from the neonatal and postnatal rats on the 1st, 3rd, 4th, 6th, 12th and 18th day of birth. Pituitary agranular primordial cells are the stem cells from which acidophils develop. During embryonic life, the male is more advanced in differentiation of primordial cells than the female. Initial granulation begins to take place in “ambiguous cells” (Yoshimura et al., 1970) on the 17th day of gestation as a row of minute granules about 50 mμ along the plasmamembrane. Incidence of ambiguous cells with various shapes is higher in the male than in the female. During embryonic period, only a small number of immature acidophils have developed from ambiguous cells despite spherical enlargement of cell-bodies where dense granules maintain their size within the proximity of 250 mμ. Most of ambiguous cells tend to transform into immature basophils, and even gonadotroph-like basophils have accumulated during the latest pregnancy. On the other hand many immature acidophils emerge directly from primordial cells without the mediation of ambiguous cells. In a certain primordial cells, a row of dense granules as large as 130-200 mμ in diameter suddenly appear along the plasmamembrane on the 18th day of gestation. In equilibrium with the prompt increase in the cell number, their granules rapidly increase in dimension and their maximal size reaches 250 mμ towards the end of fetal period. Postnatal development of acidophils is quite quick as to the population and granulation in both sexes. Numerous immature acidophils, not always spherical but somewhat elongated, develop appositionally from primordial cells. Appearance of a row of large granules of 200-250 mμ along the plasmamebrane of primordial cells seems to be related to morphological representation for the main developmental process of acidophils. Granules in immature acidophils increase in number, their size being persistently less than 200 mμ up to the 6th postnatal day. Enlarged spherical premature acidophils containing numerous granules of 200-300mμ in diameter begin to appear on the 12th day. So-called somatotrophs identical with the fully developed acidophils filled with large granules of about 350 mμ start to appear on the 18th day of age.

The effect of salts on the pars distalis of R. cyanophlyctis was studied by placing them in sodium chloride, potassium chloride (0.5%), distilled water and tapwater (control) for 15 days. In frogs kept in NaCl solution basophil type 3 cells (B3) showed marked hypertrophy and degranulation, whereas the B3 cells of frogs kept in KCl solution showed the hypertrophy and accumulation of secretory granules inside their cytoplasm. The B3 cells of frogs kept in distilled water or tapwater showed no changes. The other cell types of the pars distalis (A1 and A2 acidophils; B1 and B2 basophils) remained unaffected. It is concluded that the B3 cells are the probable source of adrenocorticotrophin and that the adenohypophyseal hormone(s) play a role in the maintenance of water and salt balance in R. cyanophlyctis.

As early as 1932, basophil cells have been considered to be involved in the corticotropic and melanotropic functions due to their proliferation during Cushing’s disease. Later on, opposite opinions were held and other cells suggested to be implied in the tumor process: chromophobe, acidophil or even follicular cells. Moreover, new categories of basophil cells have been evidenced through sophisticated staining methods, in animal and human pituitaries. At the same time, the prevalent dogma ‘one hormone-one cell’ raised the problem of the search for both a corticotroph and a melanotroph in the human pituitary, which is devoid of an intermediate lobe. Since 1960, immunocytochemistry became a reliable method and simultaneously new peptides have been found. However, these peptides share common sequences of amino acids, thus raising questions as to the specificity of the antisera. Most authors mention the reaction to the basophil cells previously considered as melanotrophs and called β or R [here β(R)]. These large rounded cells, showing red granules after Alcian blue-PAS staining, are mostly located in the median area of the anterior lobe, in the cystiform zone and in cell cords invading the neural lobe. In the fetal pituitary, reactivity is observed either in some differentiated β(R) cells or, earlier, in chromophobe cells.The question is now raised whether one cell may contain several peptides and, in this case, whether the different peptides are carried by the same granule. Technical procedures using numerous antisera on serial sections have shown associations at the level of a given cell (and of a given granule under the electron microscope). However, dissociations are also to be noticed, as far as ACTH and β-MSH (adult) and more particularly α-MSH (adult and fetus) are concerned.

[Owing to the study of various stained preparations, the histological features of the neurosecretory cells and the distribution of these elements in the nerve centres of Asellus aquaticus (L.) have led to distinguish seven types of neurosecretory pericaryons. β and y cells are located in the protocerebron whereas basophil 1 and 1' cells are widely distributed in the whole central nervous system. The acidophil 2 neurosecretory pericaryons are found among the optic lobe neurons and the acidophil 2' neurosecretory cells are located in the ventral cortex of the mandibular ganglion. An isolated fusiform neurosecretory cell is inclosed in a neurohaemal formation. Two sinus nerves drain the secretory product, the migration of which along the axons greatly facilitates study of their complex course from the protocerebron to the pleotelson ganglion. The sinus nerves pathway presents connections with the nerve centres and includes several neurohaemal structures in which the neurosecretory product accumulates. The existence of metameric neurohaemal formations connected to the nervous cord is described for the first time in Peracarida., Owing to the study of various stained preparations, the histological features of the neurosecretory cells and the distribution of these elements in the nerve centres of Asellus aquaticus (L.) have led to distinguish seven types of neurosecretory pericaryons. β and y cells are located in the protocerebron whereas basophil 1 and 1' cells are widely distributed in the whole central nervous system. The acidophil 2 neurosecretory pericaryons are found among the optic lobe neurons and the acidophil 2' neurosecretory cells are located in the ventral cortex of the mandibular ganglion. An isolated fusiform neurosecretory cell is inclosed in a neurohaemal formation. Two sinus nerves drain the secretory product, the migration of which along the axons greatly facilitates study of their complex course from the protocerebron to the pleotelson ganglion. The sinus nerves pathway presents connections with the nerve centres and includes several neurohaemal structures in which the neurosecretory product accumulates. The existence of metameric neurohaemal formations connected to the nervous cord is described for the first time in Peracarida.]

Spore preparation of Bacillus thuringiensis israelensis fed to the silkworm larvae induced histopathological and histochemical changes in the midgut epithelium. The toxin penetrated the peritrophic membrane and affected the epithelial cells. Histopathological changes observable with a light microscope included hypertrophy of epithelial cells, vacuolation of cytoplasm (and nuclei) disruption of the microvilli, eversion of plasma membrane, disappearance of basal striations, necrosis of nuclei, disorganization of cytoplasmic organelles, and disintegration of the cell. Histochemical changes observed in the columnar cells were: Loss of basiphilia due to fall in RNA, decreased protein content, and increased uptake of glycogen. Instead of the term “goblet cell”, the name “acidophil cell” is suggested on the basis of its histochemical properties.

Prolactin (LTH) and growth hormone (GH) containing cells in A. guldenstaedti have been localized by means of anti-ovine prolactin and anti-bovine growth hormone respectively, coupled indirectly to peroxidase, and localized histochemically with hydrogen peroxide as substrate and 3,3′-diaminobenzidine as capturing agent. The distribution of the anti-prolactin positive cells has been demonstrated and correlated histologically with the acidophilic cells both in the rostral and proximal pars distalis. This cell type is elongated and arranged in follicles in the rostral pars distalis; in the proximal pars distalis they are smaller and oval, without any special orientation. Neither of the other cell types which are scattered among these acidophils contain prolactin. The anti-bovine growth hormone positive cells are evenly distributed in the proximal pars distalis above the hypophysial cleft, and some are also found in the pars intermedia. The anti-GH positive cells have been correlated histologically with the amphiphilic cells in the proximal pars distalis. These cells are arranged in cell cords in close contact with the secondary capillary plexus, near its origin from the primary capillary plexus covering the median eminence.

The induction of pathologic changes with hormone steroids has been studied in rodents, although comprehensive studies are lacking on the potential reversibility of these lesions. For these purposes, groups of rats were treated with quingestanol acetate and quinestrol, a progestogen-estrogen combination, for 50 weeks and observed for a subsequent 30-week period. Treatment resulted in a significant body weight gain suppression and reduction of food consumption which recovered after withdrawal. Other significant treatment-related effects were hair loss, ataxia due to pituitary enlargement, mammary chain masses with histologic adenocarcinoma, lens opacities, ovarian atrophy with follicular arrest, and uterine atrophic changes with suppurative inflammation throughout 50 weeks. Cessation of treatment did not effect hair loss or lens opacities, while mammary chain masses decreased in size and in incidence; mammary gland tumors showed regressive changes including the disappearance of adenocarcinoma, and the incidence of ataxia diminished together with reduced pituitary weights. Chromophobe cell hyperplasia with decreased eosinophils and acidophils and hemorrhage into the pituitary was observed up to 50 weeks and the tinctorial affinity of basophils and acidophils returned after withdrawal. Ovaries and uteri, which become atrophic and sustained chronic suppurative inflammation in the treatment phase, showed reduction of inflammatory reaction and disappearance of suppuration after withdrawal, and endometrial regeneration occurred with luteal cells seen in the ovaries. These results revealed the regressive characteristics of some of the mammary gland carcinomas as well as steroid-induced endocrine and pathologic lesions other than tegumentary and ocular changes in rats receiving high levels of steroids for prolonged periods of time.

The process of development of thyroidectomy (TX) cells from the so-called thyrotrophs (the H-type cells by Yoshimura et al., 1977) was electron-microscopically investigated at intervals of 12 hr, 1, 3, 5, 7 and 14 days after TX. Cytological changes of the II-type cells vary from cell to cell even at the same intervals after TX. From 12 hr to 5 days, the II-type cells are characterized by the deprivation of secretory granules and the enlargement of cell size. When extensively degranulated, the II-type cells appear as vesiculated cells with a round or oval shape, resembling the LH-gonadotrophs (the III-type cells). The frequent detection of III- and IV-type cells (FSH-gonadotrophs) is in striking contrast with the infrequent detection of IItype cells within 12 hr and 1 day. Some pre-existed IV-type cells show retrogressive signs after TX. Some other IV-type cells are moderately granulated, at 1, 3 and 5 days, followed by the deprivation of the stored secretory granules, resulting in the vesiculated cells. These cells begin to appear at 3 days and increase in number at 5 and 7 days, despite the individual disparity in development. They may be the immature TX-cells characterized by the closure of Golgi lamellae, and by granules of low density in the small, irregularly shaped cisternae. They gradually increase in dimensions with the lapse of time. Degranulation and accumulation of large cisternae with progressive sedimentation of intracisternal granules may account for the maturation of TX-cells. By 14 days the maximal diameter of the mature TX-cells becomes 3-4 times as large as that of an acidophil. From the present observations, it is tentatively concluded that TX cells may not directly develop from the II-type cells, but indirectly through the III- or IV-type cells; and that the TX-cells may not be hyperfunctioning thyrotrophs, but rather dysfunctioning basophils.

The anterior lobe of the rat pituitary was investigated immunohistochemicallly as to nervous tissue-specific S100 protein. Granulated cells, both acidophils and basophils, were not stained with peroxidase-labelled anti-S100 rabbit serum (Fab) by the direct staining method. Only stellate-shaped cells with long slender cytoplasmic processes contained nervous tissue-specific S100 protein in the nucleus and cytoplasm, the presence of which was verified by both light and electron microscopic immunohistochemistry. Folliculostellate cells were devoid of specific secretory granules and in areas formed follicles with numerous microvilli and junctional complexes. They often extended long cytoplasmic processes between granulated cells. Ouchterlony double diffusion tests confirmed the presence of S100 protein in the pars distalis of rat pituitary glands. These findings lead to the hypothesis that folliculostellate cells may belong to the neuroectodermal cells and may be specialized cells playing some unknown role in rat adenohypophysis.

The pituitary gland of Latimeria chalumnae is situated rostroventral to the telencephalon. The hollow pituitary stalk is bent forward and is ventrally connected to a saccus-vasculosus-like organ, rostrally to a neurointermediate lobe. The infundibular lumen protrudes far into the neurohypophysial lobules. The elongated principal part (pars cerebralis) of the pars distalis is partly embedded in a dorsal depression of the pars intermedia and caudally invaded by the neurohypophysis. It may be divided into rostral and proximal pars distalis and includes a ramified hypophysial cleft, which continues rostrally as a duct with adjacent islets of pars distalis tissue (parts of a pars buccalis). The adenohypophysis consists of cell cords and follicles. Eight tinctorial cell types can be distinguished: in the rostral islets: large basophils with acidophil globules, in the rostral pars distalis: small basophils, large basophils with amphiphil characters and erythrosin-, orange G-positive acidophils; in the proximal pars distalis: orange G-positive acidophils and small and large basophils, having similar staining properties; in the pars intermedia: one amphiphil cell type.

Endocrine glands of the ironfish were studied light microscopically to elucidate the relationship between the races of the genus Carassius. The rostral pars distalis of the adenohypophysis consists mainly of acidophils corresponding to prolactin cells and lead-hematoxylin positive cells corresponding to corticotrophs (ACTH cells). The prolactin cells are obviously arranged in the form of follicles. The proximal pars distalis contains orangenophils (STH cells) and two types of basophils (TSH and GTH cells). In the pars intermedia, three types of cells are identified: periodic acid Schiff positive cells, lead-hematoxylin stainable cells and orangenophils containing PAS positive coarse granules. In addition, small agranular cells are seldom demonstrated in the entire adenohypophysis. A considerable amount of aldehyde fuchsin positive neurosecretory material is laden in the cells of the nucleus preopticus and in the pars nervosa. The nucleus lateralis tuberis is composed of three portions: pars anterior, pars posterior, and pars lateralis. The thyroid follicles found in the pharyngeal region and head kidney show a mild state of activity. The interrenal cells intermingled with the chromaffin cells have a considerable amount of eosinophil cytoplasm. Judging from the gonadal condition, the breeding season of the ironfish may extend to the end of July.

Since its clinical description in the last century, much progress has been made in our understanding of acromegaly. From an initial description of pituitary enlargement as just another manifestation of generalized visceromegaly, the pituitary abnormality has come to be recognized, in most instances, as the underlying aetiological factor. Gigantism and acromegaly are manifestations of disordered pituitary physiology, but the lesion responsible may be hypothalamic, adenohypophyseal or ectopic in location. The best known pathological hypothalamic basis for acromegaly is represented by a neuronal malformation or 'gangliocytoma'. It usually takes the form of an intrasellar gangliocytoma or, more rarely, a hypothalamic hamartoma. The neuronal elaboration of GHRH may play a role in the development of a growth hormone adenoma; the pituitary process may pass through an intermediate stage of somatotropic hyperplasia. When acromegaly has its basis in a pituitary abnormality, the lesion is almost exclusively an adenoma; the non-tumorous adenohypophysis shows no evidence of coexistent hyperplasia. Surprisingly, such tumours are more often engaged in the formation of multiple hormones rather than GH alone. They frequently produce not only GH and prolactin, the products characteristics of cells of the acidophil line, but also glycoprotein hormones, usually TSH. The spectrum of adenomas also varies in its degree of differentiation from a histogenetically primitive lesion, the acidophil stem cell adenoma, to well-differentiated tumours of varying cellular composition and hormone content. Each adenoma type has its clinicopathological, histochemical, immunocytological and ultrastructural characteristics. The isolation and characterization of GHRH has permitted the identification of neuroendocrine tumours, most of foregut origin, elaborating this releasing hormone. Such functional tumours induce hyperplasia of pituitary somatotrophs and may, on occasion, result in the formation of growth hormone adenomas. Resection of these GHRH-producing neoplasms results in reversal of endocrinological and sellar abnormalities. Future efforts should be directed toward the elucidation of the aetiology of pituitary adenomas, specifically whether they represent a proliferative process having its origin in endocrinological imbalance, presumably a hypothalamic abnormality, or whether it has a 'de novo' origin in the 'usual process of neoplastic transformation'.