TOTAL HEMOCYTE COUNTS AND HEMATOPOIESIS IN SADURIA-ENTOMON (LINNAEUS,1758) (ISOPODA, VALVIFERA) FROM THE BALTIC SEA INFECTED WITH THE YEAST CRYPTOCOCCUS-LAURENTII (KUFFERATH) (SKINNER)

Studies were made of the haemolymph and haematopoiesis of 22 specimens of Saduria entomon, naturally infected with the yeast Crytococcus lau reptii. In 18 of these haemocytes were also counted. Their total haemo cyte count was 693, which is 3 times the figure in healthy S. entomon. Their haemolymph contained granulocytes, hyaline cells, and C. lauren tii cells. Granulocytes contained phagocytosed C. laurentii cells, whi le hyaline cells did not contain phagocytosed yeast. Haematopoiesis wa s clearly taking place in the gut wall of the S. entomon specimens und er study. In the 4 remaining individuals the haemolymph was filled wit h C. laurentii cells among which only single hyaline cells with phagoc ytosed yeast cells were observed. In their gut wall only yeast cells a ccumulated. The results obtained support our earlier findings that in S. entomon granulocytes are the primary phagocytotic haemocytes, and t hat hyaline cells can be taken to be prohaemocytes capable of prolifer ation under specific conditions.