[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.