[Comparative analysis of seasonal changes in the hematopoietic processes in the spleen and peripheral blood of the common frog. II. Thrombocyte and neutrophil series].

Dynamics of the appearance of immature forms of the thrombocytic and neutrophilic cell lineages in the blood of the grass frog was studied during the forced cessation of hibernation. The thrombocytic lineage cells were classified into three maturation stages, their morphology being described. In winter, immature cells of both the lineages are present in hemopoietic tissue and occasionally in blood. Under the action of warm, they rapidly increase in number, within the next 1-2.5 days. The number of cells being at various stages of maturation in the blood of each animal showed, during the experiment, synchronous and similarly directed changes. A proposal is made that the maturing thrombocytes and neutrophils may pass easily the blood-spleen barrier without making any limited population in the blood. By this they differ from the erythroid cells which develop within the blood flow in summer as an independent synchronous population. Seasonal changes in migration rates of the newly formed thrombocytes and neutrophils into the blood were studied using thymidine autoradiography. The entry of these cells into the blood proved to be limited in winter and in spring. It means that a kind of seasonal regulation exists in the functioning barrier between the hemopoietic tissue and the blood.