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In the hypothalamus of the roach ( Leuciscus rutilus) green and yellow fluorescent cells were found in the nucleus recessus lateralis (NRL) and the nucleus recessus posterioris (NRP) and green fluorescent cells in the nucleus recessus preopticus (NRPO). The green fluorescence indicates the presence of noradrenaline or dopamine and the yellow one the presence of 5-hydroxytryptamine. The cells of the NRL and NRP contained electron dense granules averaging 70 nm in diameter. The NRL is divided into two parts. These and the NRP are connected by large fluorescent tracts. The NRL and NRP send axons towards the nucleus lateralis tuberis (NLT) and the NRPO sends axons towards the nucleus preopticus (NPO). It could not be established whether the aminergic nuclei described are the origin of the fluorescent fibers in the hypophysis of the roach. [ABSTRACT FROM AUTHOR]

Fluorescent (aminergic) fibers were demonstrated by the Falck-Hillarp technique in all parts of the neurohypophysis (NH) in the roach ( Leuciscus rutilus). The fibers are very thin and few in number in the rostral (RNH) and proximal neurohypophysis (PNH) but slightly more numerous in the NH adjacent to the pars intermedia (PI). The fibers occur in normal fish as well as in specimens pre-treated with α-methyl-noradrenaline. It is proposed that all parts of the adenohypophysis have a very sparse aminergic innervation. There is no correlation between the number of type 'B' fibers and fluorescent fibers in the roach NH. The technical difficulties in obtaining good and reliable results in teleost material are discussed. [ABSTRACT FROM AUTHOR]

An examination of cell contacts was made in the atrial and ventricular muscle of Teleost fish. The intercalated discs consist of two types of junction resembling fascia and macula adherens. Small focal areas of gap junctions were shown to be numerous away from the regions of intercalated disc between the myocardial cells. [ABSTRACT FROM AUTHOR]

The morphology of the sarcoplasmic reticulum in myocardial cells of the ventricle of the trout heart is described as the result of an investigation with the electron microscope. The sarcoplasmic reticulum is sparse in distribution compared to that of birds or mammals but shows a fundamentally similar organization. A very loose network of fine tubules is in intimate contact with the myofibrils but with no local modification with respect to the arrangement of myofilaments within the sarcomeres. There is no special association of the sarcoplasmic reticulum with the Z-bands. Some tubules pass to the cell periphery where they expand to form subsarcolemmal cisternae in which electron-dense matter is often seen. The occurrence of the subsarcolemmal cisternae (peripheral couplings) is random and they are not observed in the vicinity of intercalated discs. The sarcoplasmic reticulum is discussed in relation to excitation-contraction coupling in teleost myocardial cells, and in comparison with that of other vertebrates. [ABSTRACT FROM AUTHOR]

In order to identify the thyrotropic cells in the pituitary gland of Cichlasoma biocellatum, adult animals were treated with thyroxine. Periodic acid Schiff (PAS)- and aldehyde fuchsin (AF)-positive, and Alcian blue (AB)-negative basophils in the meso-adenohypophysis as well as the thyroid were strongly inactivated by such treatment. Since other cell types in the adenohypophysis were not affected, it is concluded that the PAS-positive and AB-negative basophils in the meso-adenohypophysis are the thyrotrops. In normal animals the thyrotrops and the thyroid are very active. Propylthiouracil did not cause a further activation of TSH cells. Keeping the animals in 25% sea-water caused a strong inactivation of the prolactin cells, the thyrotrops and the thyroid. In deionized water the prolactin cells were stimulated, but the thyroid was less active than in controls. Injections of ovine prolactin did not enhance the activity of the thyroid in salt water animals. It is suggested that in Cichlasoma biocellatum prolactin does not have a direct stimulatory effect on the thyroid. [ABSTRACT FROM AUTHOR]

In the adenohypophysis of Cichlasoma biocellatum, which may be divided into a pro-, meso-, and meta-adenohypophysis, seven cell types can be distinguished. Treatment with deionized- and salt water effects three of these cell types. The rostral acidophils, which were proved to produce prolactin by means of an immunochemical method, are distinctly stimulated in deionized water and markedly inactivated in 25% sea-water. The putative ACTH cells, bordering neurohypophysial branches in the pro-adenohypophysis, are moderately stimulated by both treatments. The presumptive TSH cells, which in control animals appear to be very active, do not show marked changes in deionized water; they are strikingly inactivated, however, in salt water specimens. [ABSTRACT FROM AUTHOR]

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The problem of the endocrine significance of the atretic follicle in the ovary of fishes has been approached with histological and cytological methods in the Guppy, Poecilia reticulata. The atretic follicles are subdivided into four stages: α-, β-, γ-, and δ-stage. During the period of pregnancy, lasting approximately one month, the atretic follicles were irregularly present. In 50 out of 73 animals, they were entirely absent. This appeared to have no influence upon a normal pregnancy; consequently, endocrine activity of the atretic follicle is not probable. The results of the cytochemical test also pointed in this direction. Enzymes, essential for steroid synthesis could not be proved to be present. Acid phosphatase and E-600 resistant esterase, however, were found in considerable amounts, indicating the presence of lysosomal activity. These results clearly show that the atretio follicle of the Guppy does not produce steroid hormones. Consequently, it is preferable to use the name Corpus atreticum instead of Corpus luteum praeovulationis. Moreover, it appears from cytochemical results that the degeneration process of the follicle can be subdivided into two phases: primarily the resorption of the oocyte during the α-stage, and secondly the regression of the granulosa cells during the subsequent stages. [ABSTRACT FROM AUTHOR]

Autoradiography has been employed to investigate the site of origin of the adepithelial basement membrane, or basal lamina, of the skin of Fundulus heteroclitus. Both tritiated glucose and proline were used as radioactive precursors in organ culture. Glucose was progressively segregated and concentrated in two areas of the epithelium: (1) in the superficial layer of cells near the external surface, and (2) in the cortex of the basal layer near the basement membrane. After 12 hours the basement membrane was also labeled, and after 24 hours the epithelium, basement membrane (basal lamina), and basement lamella were all labeled. We have concluded that the label over the superficial layer of epithelium near the external surface of the fish represents glucose incorporation into mucous secretion products; and that label over the basal cell layer, basement membrane, and basement lamella represents synthesis by the epithelium of glucose-rich components, perhaps mucoproteins, of the basement membrane and of the ground substance of the basement lamella. Not all areas of the epithelium and underlying connective tissue incorporated glucose at the same time, and only after 24 hours were unlabeled areas of the skin eliminated. Proline incorporation was much less specific than that of glucose. Although the epidermis and dermis were heavily labeled, proline was incorporated in almost every tissue of the fish. The value of proline as a specific label for collagen is questioned. [ABSTRACT FROM AUTHOR]

The development and activity of the basophils in the meso-adenohypophysis of Anopthichthys jordani were studied in relation to the maturation of the gonads. In addition, pituitaries and ovaries of post-spawning females were studied during a period 0-11 days subsequent to spawning. The large and mainly PAS-positive basophilic cells in the meso-adenohypophysis were the only cell type that showed a correlation with the development and maturation of the ovaries and testes. These cells were subjected to a partial or complete degranulation in females following oviposition, when yolk formation in the ovary was at a maximum. It is concluded that the large PAS-positive basophils in the mesoadenohypophysis have a gonadotropic function and that only one gonadotropic cell type is present in the adenohypophysis of Anoptichthys jordani. [ABSTRACT FROM AUTHOR]

In order to identify the TSH cells in the pituitary gland of Anoptichthys jordani, the development of the adenohypophysial cell types was studied in relation with the differentiation of the thyroids. In addition experiments were performed in young and adult animals with propylthiouracil (PTU) and thyroxine. At the time of the first thyroid development two meso-adenohypophysial cell types in the pituitary gland of Anoptichthys jordani are distinctly differentiated: orangeophilic cells and Alcian Blue (AB)-positive basophils. Because thyroxine and PTU could evoke changes in activity of the latter but had no effect on the orangeophils, it is concluded that the angular AB-positive basophils in the meso-adenohypophysis of Anoptichthys are responsible for the TSH production. PTU and thyroxine were unable to affect TSH cell activity in adult animals. [ABSTRACT FROM AUTHOR]

The pancreatic islets of Carassius carassius have been studied by electron microscopy. 1. Besides A-, B- and D-cells, two new cell types, the fourth and the fifth, have been identified. The fourth cell type is numerous; it occurs interposed among the other types of islet cells or in small clusters. The secretory granules (90-280 mg in diameter) are round or oval and usually with much lower electron density than α- and δ-granules. The secretory granules of the fifth type of cell (approximately 140-240 mμ in diameter) contain finely granular material and an electron dense core that is round or often tetra- or hexagonal. 2. The islet cells with clear cytoplasmic matrix generally contain large numbers of fine, agranular and cored vesicles 400-680 Å in diameter. They appear, in bead-like chains, or randomly scattered throughout the cytoplasm, or often clustered in aggregates close to the secretory granules and show evidence of incorporation into the secretory granules. The two types of vesicles may be formed by constriction or pinching-off of the tubular smooth endoplasmic reticulum. [ABSTRACT FROM AUTHOR]

Copyright of Zeitschrift Für Zellforschung und Mikroskopische Anatomie is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Zeitschrift Für Zellforschung und Mikroskopische Anatomie is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Zeitschrift Für Zellforschung und Mikroskopische Anatomie is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Tissue from the four chambers of the heart of the plaice ( Pleuronectes platessa, L.) has been examined in the electron microscope in order to describe the morphology of the heart at a fine structural level. The sinus venosus is a thin walled chamber between 60-90 μ thick consisting of a connective tissue matrix in which are situated the plexus of the parasympathetic cardiac ganglion and localised bundles of myocardial cells. The myocardial cells do not form a continuous layer but are associated in particular with the region of the cardiac ganglion and are innervated by it. The sino-auricular junction has hitherto been described as a pacemaker region but the myocardial cells in this region are identical in morphology to myocardial cells in other parts of the heart. There is a large complex of nerves, derived from the cardiac plexus, that runs around the junction before branching to innervate the auricle. The myocardial tissues consist of an outer layer of myocardium forming the wall of the heart and a profusion of trabeculae. The endocardium invaginates into the endocardium to divide up the cells into populations of approximately 25 cells in profile. There is no well-defined coronary blood supply although capillaries are occasionally seen. The myocardial cells themselves are small in diameter (3.5-5.5 μ) and show some primitive features which are: a short sarcomere (1.4-2.0 μ), the absence of any sarcoplasmic reticulum, and very scarce fasciae occludentes. In the atrium in particular, there are many groups of 1500 Å membrane-bound, dense-cored vesicles in the myocardial cells. Ventricular cells contain more myofilaments and mitochondria than do atrial cells and have many vesicles of 0.1-0.3μ diameter whose function and contents are unknown. Connective tissue is very evident in the plaice heart, being an integral part of the sinus venosus and the auriculo-ventricular junction and being the sole constituent of the auriculoventricular valve and the bulbus arteriosus. [ABSTRACT FROM AUTHOR]

The histological differentiations of myotomes and myosepts in the teleost Brachydanio rerio were studied in relation to function and shape development of the myotomes. The presence of contractile elements, intercellular space, growth by cell proliferation and the collagenous structure of the myosepts were considered as important characteristics. To a certain extent, the first deformations of the somites could be explained with these characteristics. It is suggested that firm attachment of the myosept collagen to the notochord sheath and the asymmetrical growth of the myotomes, might be of importance for the development of the oblique orientation of the muscle fibres. The sequence of the differentiation processes is not the same for all muscle cells. Cells next to the notochord synthetize myofilaments before they become polynuclear, while cells elsewhere in the myotome become polynuclear by fusion before they start to synthetize myofilaments. Some aspects of the histological differentiation of the myotomes in B. rerio were compared with myotome development in the chick, Gallus domesticus. [ABSTRACT FROM AUTHOR]

An electron microscopic study has been made on the development of the heart of the plaice ( Pleuronectes platessa L.) by the examination of tissue taken from fish at the stage when the heart-tube has formed right through the larval life and up two months postmetamorphosis. The process of developments of the heart is essentially the same as that in higher vertebrates but there are certain minor sequential differences with comparable chick tissue. By day 24 (ten days after hatching) the 'early larval' heart has formed which is a trilaminar structure - a layer of myocardium bounded internally by endocardium and externally by epicardium. This condition lasts until the 4a (Ryland) stage with the onset of endocardial invagination into the myocardium which is the criterion distinguishing the 'late larval' heart. The 'late larval' heart lasts throughout metamorphosis of the larva and until two months post-metamorphosis when the total adult heart is assumed. Thus the process of cardiogenesis continues irrespective of hatching and of metamorphosis. This study supports the concept that the epicardium is derived from an extramyocardial source. No results are presented concerning the theory that, in its earliest stages, the myocardium has a secretory function in the production of cardiac jelly, or of myofibrillogenesis in the Teleost myoblast. Stellar configurations of short lengths of newly formed sarcomeres commonly radiate out from Z centres in early myocytes and it is suggested that this is a primitive feature of Teleost myogenesis. There is also a proliferation of mitochondria within the myocardial cells at metamorphosis which may be connected to the subsequent fast growth of the heart in the succeeding two months. [ABSTRACT FROM AUTHOR]