The middle ear in the ontogenesis of mammals

The middle ear in mammals is characterized by structural variations and a broad spectrum of adaptive transformations related to peculiarities of species ecology, but it preserves the general basic principle of structure in most mammals. In species remote from a phylogenetic point of view but close in ecologic specialization, features of parallelism are observed concerning the development of separate elements of auditory ossicles as well as the way of their interconnection and attachment to the tympanum. Along the way to the adaptation to the water lifestyle in semi-aquatic and aquatic species, new additional structures, not intrinsic to initial terrestrial forms, have been formed. The use of ecological and morphological approaches to research the peripheral division of the auditory system of mammals with different ecological specialization in the ontogenesis permitted us to reveal that peculiarities of its structure in different groups of mammals are preconditioned by the animals’ adaptation to specific acoustic properties of their environment. Morphological and functional adaptations of the peripheral auditory system aimed at optimizing auditory sensitivity in the environments differing in physical properties are of great importance in evolution. Adaptive specific features in the structure of the middle ear in aquatic species appear at early stages of development in spite of intrauterine growth without the direct influence of environmental conditions.     

Functional morphology of the bronchovascular barrier of the human lungs during various age periods

Cellular components of the bronchovascular barrier have been studied in human lungs obtained after death of some patients with acute and chronic lung inflammatory diseases, hypertonic disease, atherosclerosis and chronic glomerulonephritis. Certain oxidative-reductive and hydrolytic enzymes, including NAD-, NADP- diaphorases, lactic dehydrogenase, acid and alkaline monophosphoesterase, ATP-ase, adenylate cyclase and nonspecific esterase were evaluated quantitatively after the histochemical processing of the specimens for the above reactions. Correlation analysis was performed for the bronchial epithelium, endotheliocytes, lymphocytes, plasma and mast cells, as well as macrophages and polymorphonuclear leucocytes. The results showed that there was a significant shift in some of the measured enzymic activities. Moreover, the correlations between different quantitative data were noted and these correlations changed with age. The increase in "rigidity" of the correlations in the elements of the bronchovascular barrier has been demonstrated during the process of ageing.     

Endocrine cells of stomach epithelium in the ontogenesis of albino rats

By means of the light and electron microscopy methods structural bases of differentiation and contents of endocrine cells of the stomach epithelium have been studied during the white rat pre- and postnatal development. The development of the endocrine epithelial cells occurs in parallel with the exocrinic ones. Endocrine EC-, G-, D-, P-cells are the first to be revealed in composition of the embryonal stomach epithelium, the others--during the early postembryonic period. The differentiation of the endocrine cells is characterized with asynchronism, is accompanied with a gradual development of organells, increasing amount of secretory granules and appearance of polarity in their distribution. By the 30th day of the postnatal development, the amount of the endocrine cells in the stomach epithelium increases by 5 times in comparison to those in the 1-day-old animals, with simultaneous reaching of the high level in specific differentiation.     

Organs of hearing and equilibrium during ontogenesis of mammals

The peripheral part of acoustic analyzer was studied during pre- and postnatal development of mammals. The main trends of structural evolution of the outer, middle, and inner ear were followed in representatives of different ecological groups during postnatal development. The use of ecologomorphological approach made it possible to establish that specific structural features of the hearing organ in different mammals are determined by adaptation to specific acoustic properties of the environment. It was shown that morphofunctional adaptations directed at optimization of acoustic sensitivity in different environmental conditions were leading in the hearing organ evolution. Comparative-embryological studies of the peripheral part of acoustic system made it possible to determine the stages of formation of individual structures and establish general patterns of prenatal development of the organs of hearing and equilibrium in different mammals.     

Development of protective functions of the pig digestive tract in ontogenesis

It has been found that the state of protective functions of the digestive tract change during postnatal period. The biosynthesis and secretion of glycoproteins of mucus layer which is the main protective structure of digestive tract depend on the hormonal background and the nutrition conditions. The biosynthesis stages and secretion glycoproteins result in sexual maturity and in conditions of definitive nutrition. Opposite to that, the antiradical activity of adherent mucous layer decreases with age. The allocation of the studied components of adherent mucous layer in the stomach and in the intestine is determined.     

Organs of hearing and equilibrium during ontogenesis of mammals

The peripheral part of acoustic analyzer was studied during pre-and postnatal development of mammals. The main trends of structural evolution of the outer, middle, and inner ear were followed in representatives of different ecological groups during postnatal development. The use of ecologomorphological approach made it possible to establish that specific structural features of the hearing organ in different mammals are determined by adaptation to specific acoustic properties of the environment. It was shown that morphofunctional adaptations directed at optimization of acoustic sensitivity in different environmental conditions were leading in the hearing organ evolution. Comparative-embryological studies of the peripheral part of acoustic system made it possible to determine the stages of formation of individual structures and establish general patterns of prenatal development of the organs of hearing and equilibrium in different mammals.