OBSERVATIONS OF PRIMORDIAL GERM-CELLS IN BLOOD-SAMPLES FROM CHICK-EMBRYO

Primordial germ cells (PGC) from the circulating blood in 2-day chick embryos were observed by histochemical techniques in smear preparation and by phase contrast microscopy in fresh samples. In the blood smear, PGC were readily distinguished from blood cells by their large size (15-20 .mu.m in diameter) and by the round and large nuclei (8-10 .mu.m in diameter) occupying eccentrically the greater parts of the cells. Histochemically, they were demonstrated to contain abundant glycogen, a lesser amount of yolk granules (by the periodic acid Schiff reaction), and a large amount of lipid droplets (by the Oil red O and Sudan black B stains) in their cytoplasm. Alkaline phosphatase activity was proved slightly in their cytoplasm by the simultaneous diazo coupling method. Phase contrast microscopy showed that living PGC in the blood and from the primitive gonad of 3-day embryos changed their shape in a somewhat amoeboid fashion, suggesting their capability for locomotion as a possible mechanism of the migration of PGC in vivo.