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Nitration is one of the main reaction mechanisms of long-living reactive species (oxygen and nitrogen products) formed under the action of pulsed radiation of hot plasma. The long lifetime of reactive species formed in a discharge zone (up to several days) enables them to penetrate deep into the objects covered with a protective coat. Spores are such objects. The aim of the investigation was to study sporicidal activity of hot plasma pulsed radiation of spark electric discharge by the analysis findings of active products formed in an aqueous L-tyrosine solution under the effect of the discharge., Materials and Methods: In the study, we used a Pilimin IR-10 spark discharge generator as a source of pulsed radiation of hot plasma; a corona discharge generator - as a source of cold plasma; a DKB-9 low-pressure mercury lamp - as a source of continuous radiation of UV band, wavelength of 253.7 nm. The samples were processed in Petri dishes, 40 mm in diameter, their volume being 4 and 10 cm 3 . The study used an L-tyrosine solution in distilled water (the concentration: 160 mg/L), a suspension of bacteria and spores of micromycetes (its concentration being ~10 6 cells per 1 ml). Tyrosine conversion products were identified spectrophotometrically before and after treatment. The biocidal and sporicidal effects were assessed by counting CFU (colony-forming units) after seeding incubation at 27-37°C., Results: The oxidation of tyrosine by HO 2 • radicals was found to be impossible. Under 2 the action of nitrogen compounds, nitration proceeds with 3-nitrotyrosine formation. The nitration reaction is slow, taking about 100 h. A possible nitration mechanism is through the formation of the nitronium ion NO 2 + in an acidic medium.The biocidal effect of hot plasma radiation turned out to be weaker than that of UV radiation of a DKB-9 lamp. This is due to the difference in their emission spectrum. The sporicidal effect of hot plasma radiation was more pronounced: a 10-fold decrease in the number of CFU was observed at radiation doses of 200-280 J. Under the action of UV radiation, at the same doses, the decrease in the number of CFU was from 3 to ~30%. The sporicidal effect of hot plasma radiation is due to the decay of a long-living …ONOOH/ONOO - … complex with the formation of a nitric oxide and a nitronium ion in an acidic medium., Conclusion: The study showed the viability of spores under the action of pulsed radiation of hot plasma to decrease. While the light radiation of a UV lamp, under studied conditions, slightly penetrates the protective coating of a spore. The sporicidal effect of hot plasma radiation is due to the decay of a long-living …ONOOH/ONOO - … complex with the formation of a nitric oxide and a nitronium ion in an acidic medium. Nitration plays a decisive role in the sporicidal action of the hot plasma radiation of a spark discharge. The principle of the sporicidal effect of gas-discharge plasma radiation can be used to develop disinfecting devices.

To date, the association of an imbalance of the intestinal microbiota with various human diseases, including both diseases of the gastrointestinal tract and disorders of the immune system, has been shown. However, despite the huge amount of accumulated data, many key questions still remain unanswered. Given limited data on the composition of the gut microbiota in patients with ulcerative colitis (UC) and irritable bowel syndrome (IBS) from different parts of Siberia, as well as the lack of data on the gut microbiota of patients with bronchial asthma (BA), the aim of the study was to assess the biodiversity of the gut microbiota of patients with IBS, UC and BA in comparison with those of healthy volunteers (HV). In this study, a comparative assessment of the biodiversity and taxonomic structure of gut microbiome was conducted based on the sequencing of 16S rRNA genes obtained from fecal samples of patients with IBS, UC, BA and volunteers. Sequences of the Firmicutes and Bacteroidetes types dominated in all samples studied. The third most common in all samples were sequences of the Proteobacteria type, which contains pathogenic and opportunistic bacteria. Sequences of the Actinobacteria type were, on average, the fourth most common. The results showed the presence of dysbiosis in the samples from patients compared to the sample from HVs. The ratio of Firmicutes/Bacteroidetes was lower in the IBS and UC samples than in HV and higher the BA samples. In the samples from patients with intestinal diseases (IBS and UC), an increase in the proportion of sequences of the Bacteroidetes type and a decrease in the proportion of sequences of the Clostridia class, as well as the Ruminococcaceae, but not Erysipelotrichaceae family, were found. The IBS, UC, and BA samples had signif icantly more Proteobacteria sequences, including Methylobacterium, Sphingomonas, Parasutterella, Halomonas, Vibrio, as well as Escherichia spp. and Shigella spp. In the gut microbiota of adults with BA, a decrease in the proportion of Roseburia, Lachnospira, Veillonella sequences was detected, but the share of Faecalibacterium and Lactobacillus sequences was the same as in healthy individuals. A signif icant increase in the proportion of Halomonas and Vibrio sequences in the gut microbiota in patients with BA has been described for the f irst time., (Copyright © AUTHORS.)

Cytostatic chemotherapeutics provide a classical means to treat cancer, but conventional treatments have not increased in efficacy in the past years, warranting a search for new approaches to therapy. The aim of the study was, therefore, to obtain methacrylic acid (MAA) (co)polymers and to study their immunopharmacological properties. 4-Cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl] pentanoic acid (CDSPA) and 2-cyano-2-propyl dodecyl trithiocarbonate (CPDT) were used as reversible chain transfer agents. Experiments were carried out in Wistar rats. The MTT assay was used to evaluate the cytotoxic effect of the polymeric systems on peritoneal macrophages. An experimental tumor model was obtained by grafting RMK-1 breast cancer cells. Serum cytokine levels of tumor-bearing rats were analyzed. The chain transfer agents employed in classical radical polymerization substantially reduced the molecular weight of the resulting polymers, but a narrow molecular weight distribution was achieved only with CDSPA and high CPDT concentrations. Toxicity was not observed when incubating peritoneal macrophages with polymeric systems. In tumor-bearing rats, the IL-10 concentration was 1.7 times higher and the IL-17 concentration was less than half that of intact rats. Polymeric systems decreased the IL-10 concentration and normalized the IL-17 concentration in tumor-bearing rats. The maximum effect was observed for a MAA homopolymer with a high molecular weight. The anion-active polymers proposed as carrier constituents are promising for further studies and designs of carrier constituents of drug derivatives.

The overall objective of disease management in autoimmune diseases is to suppress chronic inflammation and prevent organ damage. Therapies often revolve around five drug classes: non-steroidal anti-inflammatory drugs (NSAIDS), anti-malarials, steroids, immunosuppressants, and bio-therapies. However, none of these is a 'cure' and each displays a potential for adverse events. In particular, while all of them suppress harmful autoimmune responses, they also impact on useful protective immune responses. T-Cell receptor (TCR) immunogenicity provides a rationale for T-cell vaccinations to induce anti-idiotypic immune responses with the purpose of down-regulating functionality of idiotype-bearing self-reactive T-cells. To explore this, in this study, 39 patients with progressive (chronic) multiple sclerosis (MS) were multiply immunized with autological polyclonal T-cell vaccines (TCVs). None of the TCV-treated patients experienced any significant side-effects during the entire follow-up period (2 years). T-Cell vaccination had no significant effects on T-cell sub-population contents in the blood of MS patients after 2 years of immunotherapy initiation. However, a substantial reduction in the frequency of CD4 +  and CD8 +  memory T-cells able to produce interferon (IFN)-γ following activation were noted in the blood of TCV-treated patients. Moreover, significant and sustained reduction in plasma IFNγ levels and concomitant increases in interleukin (IL)-4 levels were documented in these samples. The TCV-treated subjects, however, exhibited no significant changes in plasma IL-17 and IL-18. More importantly was a significant decline in proliferative T-cell responses to myelin antigens in the TCV-treated patients, indicating attenuation of myelin-specific T-cell activity. Collectively, the results suggest that polyclonal T-cell vaccination is safe to use, able to induce measurable, long-lasting, anti-inflammatory immune effects in patients with advanced MS.

The possibility of applying induced chemiluminescence was investigated to evaluate oxidative capability of the substrate under the action of hydroxyl radicals and estimate the intensity of free radical processes in biological samples based on the analysis of the organic hydroperoxyde response in a probe. For this purpose the chemiluminescence light sum was measured in 3 steps: when Fe2+ was introduced into in a sample; in course of Fenton reaction (introducing Fe2+ and H202) and when Fe2+ was introduced into the sample after Fenton reaction. Light sum was measured depending on concentration (dilution) of the sample. It was shown that the light sum reaches the maximum value at certain dilution of the substrate studied. The maximum chemiluminescence's position is determined by concentration of RH fragments being oxidized, but the chemoluminescence light sum value is determined partially by the inhibitor [InH]/[RH] and organic hydroperoxides [ROOH]/[RH] found in the sample.

Chemiluminescence of ascorbic acid in Fenton solution was investigated at acid concentration from 10(-7) to 1 mol/l. The yield of chemiluminescence exceeds spontaneous light from Fenton solution at [Asc] - 10(-4) - 10(-3) mol/l in the presence of dissolved oxygen, and prooxidant properties are displayed. When there is no oxygen in solution, this effect is not observed. A comparison of experimental data and oxidation process simulation shows that ascorbic acid is an antioxidant. Its transformation products in the presence of oxygen exert prooxidant properties.

A dependency was found between total protein content and cataract maturity (P=-0.91, p<0.01). LPO intensity sharply increased and remained stably high after appearance of lens opacity. A strict negative correlation was found between the content of polyunsaturated fatty acids in earwax and lens nucleus (P=-0.7, p<0.01). The content of conjugated dienes, crotonic aldehyde, and Schiff bases decreased during cataract development. The content of vitamins B(2), A, and E decreased with increasing brown coloration of lens nucleus. Studying the parameters of lipid metabolism in wax-producing glands of the external ear canal we can evaluate the disturbances in lipid metabolism in the lens, which was confirmed by the correlation between fatty acid composition of the earwax and lens nucleus. These data do not demonstrate the dependence of the lens state on earwax, but suggest general features of the process in organs and tissues during aging. Some markers in the blood of patients with cataract change during progress of lens opacity and intensification of brown coloration of lens nucleus, but these changes are inspecific and reflect general activation of peroxidation processes and antioxidant system.

The potentialities of diffuse optical spectroscopy for the noninvasive estimation of the oxygen state of experimental tumors have been demonstrated. The distribution of total, oxygenated and deoxygenated hemoglobin, as well as the level oxygen saturation of blood have been shown using two tumor models differing in the histological structure and functional characteristics. The results obtained by the optical method have been verified by immunohistochemical examination of tissue specimens with the exogenous hypoxia marker pimonidazole.

The capabilities of diffuse optical spectroscopy for noninvasive assessing of oxygen status in experimental tumors have been demonstrated. Specific features of the distribution of total hemoglobin, oxygenated hemoglobin, deoxygenated hemoglobin, and blood-oxygen saturation were shown on two tumor models having different histological structure and functional characteristics. The results obtained by the optical technique were verified by immunohistochemical study of tissue samples marked with exogenous marker of hypoxia--pimonidazole., (Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Patients with different forms of multiple sclerosis were treated with a vaccine consisting of myelin-reactive T cells. It was found that after this treatment, lymphocytes from patients acquired the capacity to generate antiidiotypic proliferative response directed towards myelin-reactive T cells. The serum concentration of IFN-gamma decreased about 2-fold 1.5-2.0 years after the start of vaccine therapy, whereas the concentration of IL-4 increased 2-3 fold. Myelin-reactive proliferative activity of peripheral blood mononuclear cells also decreased. The results of the 2-year follow-up study revealed no side effect of T-cell vaccination in patients with cerebrospinal form of multiple sclerosis and demonstrated its possible clinical efficiency in the treatment of this disease at early stages.

Two-staged technology for obtaining polyclonal T cell vaccine intended for the treatment of rheumatoid arthritis is described. Stage 1 includes antigen-dependent cultural selection of patient's T cells and stage 2 consists in their reproduction in the needed amounts by nonspecific mitogenic stimulation. T cell vaccination induces an effective specific anti-idiotypic immune response against T cells reactive to joint antigens. Vaccine therapy significantly reduces plasma level of IFN-gamma and increases IL-4 level. The results indicate immunological efficiency and safety of polyclonal T cell vaccine in patients with rheumatoid arthritis.

In work it is investigated influences of pulse categories on a metabolism of not purebred rats in dynamics. Research spent to the first day, through six, in twelve day after influence. It is shown, that category crown 5 of impulses and spark's category 100 of impulses, cause increase oxidations lipids for the sixth day and decrease oxidations lipids in plasma of blood and erythrocytes by twelfth day after influence. Influence category crown 50 of impulses and spark category 300 of impulses leads to increase of a level oxidations lipids on membranes erythrocytes. Categories crown 5 and 50 impulses cause dynamic changes of resistance erythrocytes. Decrease in stability for the sixth day and increase of stability erythrocytes by twelfth day after influence categorys crown is shown by pulse categories.

Nucleated erythroid cells (EC) have been previously reported to possess a potent natural suppressor (NS) activity for B-cell responses. In this study, we demonstrate that murine EC are able to reduce not only lipopolysaccharide (LPS)-driven B-cell proliferation, but also proliferative and cytotoxic T-cell responses generated in a primary allogeneic mixed lymphocyte culture (MLC); and that a soluble low molecular weight factor may be involved in such EC-derived immunoregulation. In addition, the erythroid cell-derived suppressor factor (ESF) was found to be capable of effectively reducing the allergen-driven proliferation of peripheral blood mononuclear cells (PBMC) isolated from allergic patients. From the data presented herein, it appears that ESF is heat-stable (80 degrees C for 20 min) and has molecular weight (MW) lower or close to 0.5 kDa. ESF activity is resistant to both enzyme (trypsin plus chymotrypsin) proteolysis and action of the enzymes such as lipase and phospholipase C. On the other hand, ESF is effectively inactivated by neuraminidase treatment, suggesting the presence in its structure of sialic residue(s). The neuraminidase-sensitive, ESF-like activity is readily detected in the medium conditioned with normal mouse bone marrow (BM) cells. On fractionation of low MW erythroid products on a reversed-phase C16 column in a linear acetonitrile gradient (5-95%), ESF activity is detected in the first peak alone with the shortest time of its retention by the column. The results suggest that (1) by producing ESF, EC may regulate both B- and T-cell-mediated immune processes and (2) based on its physicochemical and biological characteristics, ESF can be distinguished from each of earlier characterised suppressor mediators of bone marrow origin.

Three-component (cyclosporin A, corticosteroids and azathioprine) immunosuppression has been widely introduced in the treatment of recipients of renal transplants because it allows a significant reduction of the components' doses in greater effectiveness. The analysis of the results of 83 puncture biopsies obtained in the immediate postoperative period after kidney transplantation has shown that administration of an imidazole derivative allows raising therapeutic concentration of cyclosporin up to 200-300 ng/ml, thus preventing rejection crises. However, increased blood concentration of cyclosporin does not increase its toxicity as a result of a significant fall in the overall level of the metabolites.

Conventional drug therapy for moderate atopic or mixed bronchial asthma was combined with normobaric hypoxytherapy (NBHT) in 32 patients (a course of 10 sessions) and was not combined in 20 control patients. Clinical results show that NBHT enhances response to conventional therapy of moderate bronchial asthma as confirmed by a significant relief of the clinical symptoms, by a significant rise of volumic and flow parameters of external respiration function, a fall in the number of CD 20+ B cells, low level of serum IgE, increased number of phagocyting neutrophils and cells carrying erythroblast antigen in peripheral blood.

Tuberculosis is one of severe infectious complications in patients on hemodialysis and after kidney transplantation. Incidence of disseminated and generalized forms is high, whereas clinical symptoms are weak and nonspecific. An aggressive generalized form of tuberculosis was observed in a kidney transplant recipient. M. tuberculosis, the antigen and DNA were registered only a few days before death. Disseminated foci in the lungs were seen on CT image only in the agonal period in spite of multiple x-ray investigations. Thus, our experience and experience of other investigators evidence that if recipients of renal transplant have fever of unknown genesis and do not respond to standard antibiotic therapy, tuberculosis should be suspected and a course of specific antituberculosis therapy should be started as early as possible.

Aim: The study of effective and regulatory functions of neutrophilic granulocytes in patients with pollenosis exacerbation, correction of the impaired neutrophil function with standard treatment and specific immunotherapy (SIT)., Materials and Methods: The study included 103 healthy donors (controls) and 122 patients with pollenosis aggravation. 69 of the latter received symptomatic treatment. 53 patients received preseasonal SIT with water-salt extracts of the pollen allergens., Results: The untreated pollenosis patients had hyperproduction of interleukin-1 (IL-1) by nonstimulated blood neutrophils associated with elevation of NBT-reduction and lowering of phagocytic activity in decreasing count of Fc- and Ca-receptors. Effective SIT produced recovery of phagocytic activity, the number of Fc- and Ca-receptors, IL-1-activity of cell supernatants., Conclusion: One of the SIT targets in pollenosis patients is neutrophilic granulocytes.

A model of experimental detachment of the retina in adult newts Pleurodeles waltl was used for studies of internal sources of the neural retina regeneration. Changes in morphology, localization, behavior, and abundance of the cells of various retinal layers were studied on serial semithin and ultrathin sections of the retina taken at different times after the operation. As a result, a new class of cells was found in the external nuclear layer, which differ from the photoreceptors but have a certain morphological similarity with the bipolar cells in the internal nuclear cell layer that have a Landolt's club. These cells were called bipolar-like cells. The bipolar-like cells, which amount to 10-12% of the cells in the external nuclear layer, proved to be capable of producing new photoreceptors during retina recovery after its detachment. We propose that the bipolar cells with Landolt's club of the internal nuclear layer that are displaced towards the sclera after the death of a part of the photoreceptors are a source of the bipolar-like cells of the external nuclear layer. Supposedly, they are also a source of neuroblasts that we first found at later stages after detachment in the case of more intense destruction of the retina nuclear layers. The neuroblasts arising in the internal nuclear layer are displaced apically and divide to form radial "inserts", whose cells differentiate and restore the cell composition of all three nuclear layers of the detached retina. The discovered internal sources of regeneration of the neural retina in newts are compared with those known in fish, precursor cells of rods, and the role of other cell types in the retina regeneration is described under the given conditions of its damage.

We investigated cytoplasmic RNA from the peripheral blood cells of pollinosis patients. Increased levels of IL-I mRNA were registered in neutrophils of patients suffering from pollinosis for a long time. Neutrophils from patients at the time of exacerbation of pollinosis responded to stimuli less than the cells from healthy donors. During remission the activated neutrophils from pollinosis patients and those from healthy donors had same levels of IL-I mRNA.

The authors studied the morbidity rate accompanied by temporary incapacity for work in workers of the agricultural and industrial complex suffering from diseases of the joints. It has been established that rheumatic diseases take the first place as to their duration (number of days) and the second place at to their incidence (number of cases) per 100 workers. An annual rise in rheumatic disease prevalence, especially of a degenerative dystrophic nature was noted. Of importance are the age of patients service record in agriculture, intensity of load, nature of work, season. Machine operators were most liable to the mentioned disease.

The increased level of IL-1 mRNA was discovered in neutrophils of patients suffering from pollinosis for a long time and responding poorly to specific immunotherapy. Moreover, neutrophils from patients with exacerbation of pollinosis responded to stimuli less than cells from healthy donors. In remission, the activated neutrophils from pollinosis patients and healthy donors had the same levels of IL-1b mRNA. Tumor necrosis factor alpha expression was unchanged in neutrophils of pollinosis patients. Changes in the status of cells from patients were detected with a simple procedure of dot hybridization. Peripheral blood cells were used as available material. This allows one to hope that the approach can be used for analyzing the patients' immune status in choosing the treatment course as well as for controlling the treatment effect.

The formation of interrelations of the axons of neurosecretory cells and of ependyme cells with the capillaries of primary portal plexus in rats from the 14th day of embryogenesis till the 9th day of postnatal life was studied using the light and electron microscope methods. During the whole period under study, the basal processes of the ependyme cells reach the primary portal plexus of the capillaries. The terminals of the basal processes are usually separated from the endothelium of the capillaries by two basal membranes and enclosed pericapillary space. After the birth, some basal process penetrate in the pericapillary space and terminate on the endothelium. The surface of contact of the ependyme cell processes with the external basal membrane increases with the age, this being accompanied by the increase of pinocytotic activity. The neurosecretory axons are found in the median eminence already on the 14th day of embryogenesis, but by the 20th day only they reach the external basal membrane and penetrate sometimes in the pericapillary space. After the birth, the number of axons reaching the external basal membrane and the surface of contact between them increase gradually with, apparently, a concomitant intensification of the transport of neurohormones in the portal circulatory system of the hypophysial-hypothalamic complex.

Topographical relationships of neurosecretory axons with the capillaries of the primary portal plexus were studied in the median eminence of rats from the 14th fetal till the 9th postnatal day by means of electron microscopy combined with morphometric analysis. Special attention was given to the light and electron microscopic immunocytochemical examination of luteinizing hormone-releasing hormone projections to the median eminence. Neurosecretory axons possessing secretory granules and clear microvesicles were first observed in the median eminence at the 14th fetal day. However, all of them were situated at a distance from the primary portal plexus. By the 20th fetal day, neurosecretory axons reached the external basal lamina of the primary portal plexus giving rise to so-called axovascular contacts. Some axons even penetrated into the perivascular space, apparently facilitating the neurohormone delivery into the hypophysial portal circulation. From that time on, both the number of the axons abutting on the external basal lamina and the entire area of axovascular contacts increased gradually. As to luteinizing hormone-releasing hormone axons, they grew into the median eminence from the 18th fetal day concentrating in older fetuses and neonates either over the primary portal plexus, or around the infundibular recess of the 3rd ventricle. After birth, the concentration and distribution of luteinizing hormone-releasing hormone axons within the median eminence became similar to those of adults. Luteinizing hormone-releasing hormone axons were found to arise from the neurons of septopreoptic area including the diagonal band of Broca. These data suggest the onset of neurohormone release in the median eminence from the 14th fetal day followed by the establishment of the hypothalamic control over the pituitary functions during the perinatal period in rats.

Permeability of portal capillaries to intravascularly injected ionic lanthanum, ferritin and horse-radish peroxidase has been examined in rats on the 18th fetal day, and on days 1 and 9 of postnatal life. For several minutes, tracer molecules pass through the capillary wall and reach the median eminence. In the case of immature capillaries, the materials pass freely through the endothelial cells, and to a lesser extent are transferred via occasional plasmalemmal vesicles and fenestrae. As the maturation of capillaries proceeds their permeability via plasmalemmal vesicles and fenestrae increases considerably due to a gradual rise in the number of these structures. The plasmalemma of differentiated endothelial cells becomes impermeable to all the tracers. Only ionic lanthanum appears to penetrate through transendothelial channels and intercellular junctions between adjacent endothelial cells.

The structure of capillaries of the primary portal plexus in rats was studied on the 18th day of prenatal period and ist and 9th days of postnatal period. The number of capillaries and capillary loops penetrating in the nervous tissue of median eminence increases during development. The endothelial cells divide and differentiate and this is accompanied by the decrease in the volume of perikaryons, the flattening of peripheral cell regions and the increase in the number of fenestrae. The greatest number of pinocytotic vesicles is noted in the newborn rats. The morphometrical data obtained suggest indirectly the transport of substances through the wall of capillaries in foetuses and newborn rats mainly via pinocytotic vesicles and on the 9th day of life via fenestrae.

An electron microscopic study has been carried out in order to examine the permeability of the blood-brain barrier in the median eminence of perinatal rats. After several minutes, intravascularly injected electron-dense tracers (lanthanum nitrate; horseradish peroxidase, 40000 MW1, ferritin, 500000 MW) pass the capillary wall, the perivascular space, and become incorporated into neurosecretory axons and basal processes of tanycytes both in fetuses and young rats. In the case of immature capillaries, the materials diffuse freely through the endothelial cells, and to a lesser extent are transferred via occasional plasmalemmal vesicles and fenestrae. As the maturation of capillaries proceeds, their permeability via plasmalemmal vesicles and fenestrae increases considerably due to a gradual rise of the number of these structures. The plasmalemmata of the differentiated endothelial cells become impermeable to all of the tracers. Only ionic lanthanum appears to penetrate through transendothelial channels and intercellular junctions between adjacent endothelial cells.

Morphometric electron microscopy data were obtained using a semiautomatic image analysis which demonstrate that the main stages of formation of the external zone of median eminence in the rat hypothalamus take place during the perinatal period. From the 20th day of prenatal period to the 9th day of postnatal period, the length of contact between the neurosecretory axons and the primary portal plexus increases twice, whereas that between the basal processes of ependyma cells and the primary portal plexus by a factor of 1.5. At the same time, the number of secretory granules and microvesicles in axons and that of pinocytotic vesicles in the basal processes markedly increases. Regional differences in the distribution of vesicular structures were noted in neonatal animals: secretory granules were more numerous in the axon swellings remote from the external basal lamina; pinocytotic vesicles were more numerous in the basal processes which terminated in the medial median eminence.

The maturation of the capillaries of the primary portal plexus in rats during the perinatal period has been studied light- and electron-microscopically. The number of capillaries covering the median eminence and of those invading the nervous tissue (capillary loops) increases significantly with age. Capillary loops were observed as early as the 18th fetal day. The mitotic divisions of the endothelial cells within the preexisting capillaries seem to be the main reason for the vascular growth. Immature capillaries with a characteristic narrow lumen are surrounded by a fuzzy basal lamina; their wall is formed by a generally expanded endothelium with rather sparse organelles and inclusions, and by minute flattened areas. The maturation of the capillary results in a progressive spread of flattened endothelium followed by an enlargment of the capillary lumen. Moreover, a rising concentration of organelles and inclusions, relatively numerous luminal microvilli, and a dense and uniform basal lamina become noticeable as capillary differentiation proceeds. These data are thought to reflect the progressive increase in the metabolic activity of the endothelium as well as the establishment of capillary patency during the perinatal period of rats.