[Regulatory elements in the skin epithelium of Saccoglossus mereschkowskii (Enteropneusta, Hemichordata): electron microscopic and immunocytochemical study].

The aim of this investigation was to demonstrate the regulatory elements in the skin epithelium of Enteropneusta which are supposed to be related to the chordate ancestors. Using electron microscopy, it was found that in the skin epithelium of a representative of enteropneusts Saccoglossus mereschkowskii, the basal parts of some epitheliocytes took part in formation of a nerve layer. These cells were considered as receptor ciliated cells. The granular epithelial cells were shown to release secretion according to both exocrine and endocrine mechanism; these cells were characterized as endocrine-like regulatory cells. Fine granular cells possibly represent special receptor-endocrine-like cell type. The immunocytochemical detection of FMRFamid neuropeptide localization in histological sections confirmed the electron microscopic data on the presence of receptor and endocrine-like cells in the epithelium. It is suggested that the skin epithelium of Enteropneusta contains a peculiar neuro-endocrine regulatory system that is represented by receptor cells, receptor-endocrine-like cells of an open type and nerve elements of the nerve layer.

[Electron microscopic study of the intestinal epithelium of Saccoglossus mereschkowskii (Enteropneusta, Hemichordata)].

Epithelium of the hepatic region of the intestine in Saccoglossus mereschkowskii, a representative of enteropneusts (Enteropneusta, Hemichordata) standing at the base of Chordata, has been investigated using electron microscope. The ultrastructure of ciliated and granular epithelial cells, elements of the intraepithelial nerve layer, and intercellular junctions have been characterized. The data concerning details of the organization of the ciliary apparatus and rootlets system are presented. It is justified the presence of complicated supporting construction of cilia which performs a mechanical stabilizing function and possibly also provide synchronization of ciliary movements. The presence of cilia with two centrioles is considered as an adaptation to high functional load on ciliary apparatus. Well developed bundles of myofilaments are found in the cytoplasm of the basal portions of ciliary cells that characterizes these cells as myoepithelial. The features indicating the role of ciliary cells in absorption are described. The capability of these cells to balloon-like secretion is considered. Data on the accumulation of food reserves in the form of lipid droplets and glycogen in the cell cytoplasm are presented. Ciliated cells are characterized by their function as ciliated secretory-absorptive myoepithelial cells. Based on the location of secretory granules both in the apical and basal portions of granular cells, an exocrine-endocrine function of these cells has been suggested. Typical endocrine cells in the intestinal epithelium of S. mereschkowskii are absent. Several types of granules in the nerve fibers cytoplasm are described. Junctions between the nerve fibers and basal portions of ciliary and granular epithelial cells are found. Nerve regulation of contractile and secretory functions of epithelial cells is supposed. The presence of the regulatory nerve-endocrine system that includes receptor cells of open type, secretory endocrine-like cells and nerve elements of nerve layer is supposed in the intestinal epithelium of enteropneusts.

[Ultrastructural peculiarities of the tissue adaptation of the epithelia in some invertebrates and in man].

Using electron microscopy, the reactive changes of epidermal cells in response to hypotonic conditions were studied in the representatives of three groups of marine invertebrates characterized by different levels of organization--Convoluta convoluta (Turbellaria, Acoela), Amphiporus lactifloreus (Nemertini) and Saccoglossus mereschkowskii (Enteropneusta). On the basis of functional resemblance of absorption and pinocytosis, the peculiarities of absorptive proximal tubule epithelium of human kidney under intensive protein transport were examined at the ultrastructural level. The resemblance of the epithelial tissue reactive changes in response to the damaging was demonstrated factors in invertebrates and in humans.

[Histochemical characterization and functional significance of the epidermal gland cells in some invertebrates in phylogenetic aspect].

This paper reviews the basic results of findings on the structure and function of the epidermal gland cells in some invertebrates of different levels of organization. These data are compared with the results on the higher animals. Histochemical affinities of the epidermal gland cells in different animals are considered. The presence of the universal (ancient) cell types also found in mammals and in human is suggested. Marine invertebrate groups considered in this paper are characterized by a presence of a simple ciliated surface epithelium which fulfills different functions: locomotor, secretory, receptor, barrier, protective and absorption. In the process of phylogenesis, the epidermis of chordates underwent structural changes and intensification of protective function took place with the appearance of new protective mechanisms. The conclusion is done that the evolutionary development of surface epithelium is determined by its adaptation to environmental conditions and by the level of general organization; it followed the direction of intensification of protective function with the help of different mechanisms - mucus production, increase of cell layers number, intensive formation of cytoplasmic filaments, appearance of special protective structures in the form of cuticle or corneous layer.

[Ultrastructural characteristics of the tubular histion in the system of nephron protein reabsorption in massive proteinuria].

18 puncture renal biopsies obtained from children aged 6-12 years with primary nephrotic syndrome were studied using electron microscopic to examine the components of tubular histion in the system of nephron protein reabsorption in massive proteinuria. The results indicate changes in the interstitial connective tissue associated with collagen formation. The endothelium of peritubular capillaries demonstrated both adaptive and destructive. One of the manifestations of adaptive reactions was an additional pinocytotic vesicular mechanism of protein transport through the endothelium, described in this paper. Fenestrations are regarded as specialized cellular structures which may be formed in different cytoplasmic areas. Evidence is presented to substantiate the cascade pattern in the development of changes in the proximal tubule epithelium-interstitial connective tissue-capillary endothelium system.

[Ultrastructural characteristics of reactive changes in the epithelium of the kidney proximal tubules in massive proteinuria in children]. / Ul'trastrukturnaia kharakteristika reaktivnykh izmneneii épiteliia proksimal'nykh kanal'tsev pochki pri massivnoi proteinurii u detei.

The investigation was designed to analyse the mechanism of the protein transport on the basis of the estimation of ultrastructural organization of the epithelium of proximal convoluted tubules of kidneys of the children, suffering from the nephritic form of glomerulonephritis for a long time. It was established that high tubular proteinuria (from 0.33 to 6.6 g/l) causes many changes in apical, central and basal parts of epithelial cells as well as in intercellular spaces. It was stated that massive proteinuria provoked adaptive processes in epithelial cells of proximal tubules. At the same time signs of exhaustion of adaptive capacities of proximal nephrocytes were demonstrated.