Formation of antioxidant defence system of geese in embryogenesis and early postnatal ontogenesis

The features of antioxidant protection of tissues of a liver and blood of the gooses in embriogenesis and early postnatal ontogenesis are found out. Maximal contents TBA active products both in a liver, and in a blood are observed in 28 diurnal embriones. Is shown, that in a liver the activity of basic antioxidant enzymes (superoxide dismutases, catalase and glutathione peroxidase) in a liver is developed already at early stages embriogenesis and is considerably enlarged in the end embriogenesis. The becoming of enzymatic system of a blood descends much more slower.     

Differentiation of oxyntic cells during early ontogenesis in the bovine

The origin and the differentiation of oxyntic cells in fetal bovine abomasum were investigated using transmission electron and light microscopic methods. In the oxyntic gland region oxyntic cell precursors and immature oxyntic cells appear as early as at the end of the first trimester of gestation--much earlier than described in any other mammalian animal species. Immature oxyntic cells are characterized by long apical microvilli, by their triangular-shaped light cytoplasm rich in large and numerous mitochondria, by the existence of vesicular profiles and by the incipient invagination of the apical plasma membrane forming a primitive intracellular canaliculus expanding into central areas of the cell. The oxyntic cell represents the first exocrine cell type developing from secretory granule-containing cells in the base of the primitive gastric glands.     

Peculiarities of somatovisceral reactions in early postnata ontogenesis

To reveal possible ways of the somatovisceral interaction, in the 0–5-day, 11–13-day and one-month-old rats, reactions of the spontaneous contractile activity of the gastric antrum were studied to a rhythmic stimulation of the tibial nerve for 30 s with frequency 30 imp/s and strength equal to 3–4 thresholds of the gastrocnemial muscle motor response. Only the stimulations of the central, but not of peripheral, nerve segments were effective, which indicates the reflex nature of the reactions. It has been established that in the process of development, a shift occurs of the predominantly inhibitory reactions to predominantly activating the gastric wall reactions. Similar data were obtained by skin pain stimulation in the region of the tail base. Thus, the age-dependent change of direction of the observed somatoautonomous reactions can be produced by stimulation of different high-threshold somatic afferents. The efferent pathway both of inhibitory and of stimulatory reactions is mediated mainly, but not exclusively, by the gastric branches of the vagus nerve, which is confirmed by consequences of vagotomy and of section of the splanchnic nerve. As a whole, the results of the study can suggest that one of possible pathways of effects of the skeletal muscle contraction on rhythmic activity of the gastrointenstinal tract can be activation of muscle receptors.     

Development of the model of the cell cycle synchronization in early embryos of Danio rerio (Teleostei)

An attempt was undertaken to develop a model system based on artificial cell cycle synchronization by means of reversible mitosis blocking in zebrafish embryos for studying the role of cell cycle synchrony in embryogenesis. Dechorionized and intact embryos at the stages of 512-cell blastula and 75% epiboly were treated with nocodazole and then washed within several times of exposure. When working on dechorionized embryos, we succeeded to obtain complete block mitosis in the presence of low nocodazole concentrations: 0.5-1.0 microg/ml. Block of mitosis was relieved in all experimental series within a certain time after the beginning of washing. This inertia depended on both nocodazole concentration and duration of treatment. The nocodazole elimination was significantly accelerated only after five (or more) changes of washing medium containing DMSO. As a result, the conditions were established for obtaining a parasynchronous cell population in the zebrafish gastrulas with a peak of mitosis up to 17.2%.     

Cytodifferentiation and dynamics of intercellular relations during early ontogenesis

The paper presents ultrastructural aspects related to zygotes and embryo cytodifferentiation of Sus scrofa d., used in the biotechnology of embryo transfer, from the first division of segmentation to the stage of preimplantational blastocyst. Together with the intense cellular proliferations, the morphostructural and functional differentiation of cells takes place. First, the blastomeres are similar from an ultrastructural point of view and do not present intercellular junctions to the advanced stage of morula. Gradually, the polarity of the cellular surface is more evident (microvilli occupy only certain domains of the cellular surface and junctions of intercellular solidarity of desmosomal type occur). Ultrastructural modifications of nuclei, mitochondria and cytoskeleton are noticed. Embryoblastic cells as well as those to form the trophoblast are morphostructurally and positionally differentiated. In the stage of preimplantational blastocyst, the nuclei of some embryoblastic cells have a characteristic form of a callotte or biconcave lens with passages of nuclear material to the cytoplasm.