Effect of inorganic lead on the primordial germ cells in the mouse embryo.

Embryos from mice exposed to lead chloride (20 micrograms/gm body weight) by a single intravenous injection on day 8 of gestation were examined regarding the number and distribution of their primordial germ cells on 4 consecutive days of development. The cells, visualized by histochemical staining for alkaline phosphatase, showed a normal body distribution but were significantly fewer at all four stages compared with those of control embryos of corresponding age. Furthermore, the staining of the primordial germ cells was much weaker in the embryos from the lead-treated dams than in those from control dams, suggesting that the lead had interfered with the production or activity of alkaline phosphatase. It is assumed that these effects could have contributed to the fertility reduction previously observed in female offspring of mice exposed to lead at an early stage of pregnancy.