[Morphological analysis of hemocytes of ascidian Halocynthia aurantium].

The current paper is devoted to the investigation of ascidian circulating hemocytes populations which are used as an example of blood cell specialization in the lower Chordates. Work has been performed on a solitary ascidian Halocynthis aurantium from the Japanese Sea. Using light microscopy and histiochemistry, we have identified five main populations of circulating hemocytes (hemoblasts, granulocytes, hyaline amoebocytes, macrophage-like and morula cells), which are typical of all tunicates. Pigment cells were not revealed. The possible pathway of circulating cells differentiation is assumed.

[Thymic mast cell localization at different stages of the ontogenesis in the mouse].

The aim of this research was to characterize the population of thymic mast cells (MC) which were demonstrated by histochemical methods, at different stages of mouse ontogenesis. First MCs appeared on day 19 of intrauterine life. MCs were localized to the thymic medulla during the whole embryonic period. Individual MCs could also be identified within the cortex. Single MCs were interspersed among other thymic medullary cells. In the newborn, young and mature animals, MCs were observed in the connective tissue of the capsule and in the interlobular septa, but some MCs were also found inside the thymic lobules. In the last-mentioned case, MCs were located in the subcapsular zone. The possible functional significance of MCs localization is discussed.

[Formation and reorganization of the early photoreception area in the eyes of sturgeon embryos and prelarvae. Radioautographic study]. / Vozniknovenie i preobrazovanie oblasti rannei fotoretseptsii v glazakh zarodyshei i predlichinok osetrovykh. Radioavtograficheskoe issledovanie.

A study of the development of eye retina in sturgeons (Acipenser güldenstädti and A. stellatus) by means of autoradiography has shown that during embryogenesis the cells of the high light sensitivity region complete the cycle of proliferation prior to the stage 29, what corresponds to the completion of proliferation of the retina cells in anurans and mammals, rather than at the stage 33, as was considered previously on the basis of the light microscopy morphological studies of differentiation. The cells of definitive retina begin to complete the cycle of proliferation at the stage 35 and the mass completion occurs at the stage 37. Some parameters of mitotic cycle were determined in the cells of definitive retina at the stages 34 and 37 and they proved to be similar with the corresponding parameters of the retina cells in anurans. The time of G2 period equals 2.5 hrs, that of S period 14 hrs and the whole mitotic cycle lasts 21.5 hrs. The transformation of the retina of high light sensitivity region in the definitive retina proceeds, mainly, by means of migration of the cells in this zone from the zone of intensive proliferation surrounding the high light sensitivity region. This transformation proceeds by means of morphological rearrangement of metamorphosis type.

[Cell population kinetics during retinal histogenesis in Rana temporaria frogs]. / Izuchenie kinetiki kletochnykh populiatsii pri gistogeneze setchatki u liagushki Rana temporaria

The histogenesis of retina was studied by means of 3H-thymidine autoradiography in the Rana temporaria embryos at the 17-25th developmental stages. At all these stages the central zone of retina is more differentiated than the peripheral one. The index of labeled nuclei in the central zone changes from 74-80 to 1.5-2.0% and in the peripheral zone from 74-80 to 60%. The outcome of the first cells from the reproduction cycle is realized beginning from the moment of the optic vesicle invagination. During the histogenesis of retina in anurans both the reproduction and the onset of differentiation of different cell types take place. The heterogeneity of the population of proliferating cells at all the stages studied proved to be similar. The data obtained are compared with those characterizing the kinetics of cell populations during the histogenesis of retina in avian and mammal embryos.