Vol 144, No 4 (2013)

Morphological characteristics of the serotoninergic neurons forming nucleus raphe obscurus (NRO), were studied in rats at the early stages (days 5, 10, 12 and 14) of the postnatal period in normal rats and in animals whose prenatal development took place under the conditions of serotonin deficiency. NRO was found to contain three subpopulations serotonin-producing neurons (large, medium and small), which had different sensitivity to serotonin level during development. The results have shown that serotoninergic system deficiency during the prenatal period resulted in the changes of NRO structural organization and in the decrease of the rate of this nucleus formation, serotonin-producing neurons differentiation and the reduction of their total number by approximately a factor of 1.6. At the same time, the significant changes of the dimensions of serotoninergic neurons of all types took place. In control animals, the size of large, medium and small neurons was 1.8, 1.4 and 1.5 times greater than that in experimental animals, respectively. Reduction of the neuron dimensions was associated with the changes of a nucleo-cytoplasmic ratio. The volume of the cytoplasm and of Nissl bodies was significantly decreased. Along with it, the cell destruction was noted that increased with age. Synchronously with it, the marked astrocytic reaction developed, which could further lead to gliosis.

The structural peculiarities of the thymus and cranial mesenteric lymph nodes (LN) were examined in 72 neonatal rats born to females, exposed to 15% ethanol solution during pregnancy (n=34), as well as both during pregnancy and for 1 month preceding it (n=38). 44 neonatal rats born to intact females, served as a control group. It was shown that the exposure of female rats to ethanol only during pregnancy resulted in more pronounced changes in the mesenteric LN of the offspring than in the thymus. These included the reduction of LN number, cross-sectional area, lymphoid cell relative content, the suppression of mitotic activity, increased reticular cell content and macrophage activity. Pre-gravid ethanol intoxication of females for 1 month in combination with ethanol exposure during pregnancy was shown to have greater effect on the thymus morphogenesis in the offspring. This was manifested by the decrease of its absolute and relative mass, proliferative activity, increase of cell death, appearance of the microcirculatory and dysplastic changes.

Changes in the liver were studied in 25 puppies with experimental pulmonary trunk stenosis of 6–12 months duration and 10 animals after the elimination of this defect. Control group included 10 dogs of the corresponding age. A complex of histological, morphometric, electron microscopic and immunohistochemical methods was used. During the modeling of pulmonary trunk stenosis, the resistance of hepatic afferent vessels to hepatic blood flow was increased due to the venous-arterial and venous-venous reactions. In the arteries, the bundles of smooth myocytes (SM) of the intimal muscle were formed together with the musculo-elastic sphincters, polypoid cushions, while in the branches of the portal vein, the intimal SM bundles and the valves appeared. In the efferent veins, the muscular elevations were hypertrophied. In all the vessels the thickening of the walls was observed, and in the media of the arteries, there were signs of sclerosis and the increased expression of α-smooth muscle actin (α-SMA). Hepatocytes demonstrated marked ultrastructural changes: mitochondrial matrix swelling, partial destructions of their cristae, dilation of endoplasmic reticulum cisterns. After the elimination of the defect, previously formed vascular adaptation reactions were found to disappear, the tone of the blod vessels in the liver decreased, causing the regression of hypertrophic changes of their media. The number of the arterial blood vessels with intimal muscle, sphincters and cushions decreased. The expression of α-SMA in the media of the arteries was also reduced. In hepatic efferent veins, the muscular elevations became attenuated. The dystrophic changes in hepatocytes regressed at both light-microscopic and the ultrastructural level.

The reaction of the surrounding tissues to the implantation of biodegradable suture materials (plain catgut threads, DemeTECH polyglactin 910, Surgilactin — polyglactin 910) into the subcutaneous adipose tissue of rats, was studied using light microscopy 1, 2, 6 and 12 months after grafting. It was shown that the tissue reactions to implantation of different biodegradable suture materials followed the general pattern characteristic of wound healing and foreign body reaction. By the first month of observation, in all the animal groups, the stage of traumatic perifocal inflammation was replaced by a proliferative phase with the new growth of the blood vessels and connective tissue. In all the animal groups, there was a trend to reduction of productive inflammation activity from the 1 st month till the 12 th month. By the 12 th month the total degeneration of the material with full recovery of structure of surrounding tissues (restitution) was recorded only after the implantation of polyglactin 910 (DemeTECH).

In the experiment on 44 rats, histological peculiarities of tissue injury and repair were studied in the segments of caudal spine after long-term permanent and temporary (with the subsequent tale relaxation) asymmetric compression-distension (ASCD). Permanent ASCD of the tail was found to result in a complex of structural changes that were rather stable and did not disappear completely after ASCD discontinuation and a long-term relaxation. These changes included necrosis of the annulus fibrosus (AF) cells, tension of AF lamellae and their separation from epiphyses on the distension side, crushing and splitting of AF collagen lamellae on the side of compression and chondrocyte proliferation around necrotic foci, increase of necrotic notochordal cells number in nucleus pulposus (NP). Relaxation after temporary ASCD resulted in the reduction but not total disappearance of the signs of injury. Changes were noted in AF thickness, occurrence of chondrocyte necroses and the sites of collagen lamellae separation, as well as in NP displacement to distension side.

The aim of this study was to determine the possibility of immunohistochemical demonstration of various tissue antigens in paraffin sections of zinc-ethanol-formaldehyde-fixed spinal cord, surrounded by the vertebral tissues and adjacent muscles, after decalcification in formic acid, in adult (n=5) and newborn (n=2) Wistar rats. In the present work, the antibodies used were against: glial fibrillary acidic protein, neurofilaments, neuronal specific nuclear protein, enzyme tyrosine hydroxylase, protein of synaptic vesicles — synaptophysin and the intermediate filament protein — vimentin. Combination of fixation in zinc-ethanolformaldehyde and decalcification in 21% formic acid solution was shown to provide an optimal preservation of the antigens studied.

Elaboration of the concept of neural stem cells at the end of the twentieth century resulted in the appearance of the multitude of new terms used for the designation of cells localized in the proliferative zones of the brain. Concurrently, a problem arose concerning the correlation of newly named cells, generally known elements of the nervous tissue, and classic views on its development. In the present study, an attempt is made on the basis of the literature data review and authors’ own experience in the exploration of proliferative zones, to classify cell populations involved in the neurogenesis considering, primarily, the possibilities of their morphological and immunocytochemical in situ identification.