Abstract: The study defines the primordial Germ cells (PGCs) of the Early Mouse Embryo containing ALKaline Phosphatase (AKP). The other somal cells did not contain AKP. According to that, AKP is the marked enzyme of PGCs. The AKP is localized the in cytoplasm of PGCs, but the nucleus was negative. LNAse is strongly positive and it was found by the author. LNAse was more positive than AKP in the PGCs. I think that LNAse also may be the enzyme made by PGCs. There has been no report about the LNAse in PGCs. There are three kinds of PGCs. The big ceils are 30μm, the midile cells are 15-20μm and the small cells are 10μm in diameter. The big cells are different from the somal cells and the small cells are difficult to differentiate from the somal cells. We have studied ACP, NSE, ATPase, SDH, Lipin, Glycogen and G-6- Pase. They all were weakly positive or negative.

Key words: primordial germ cells, mouse embryo, histochemistry