AUTONOMOUS REGULATION OF PROLIFERATION AND GROWTH ARREST IN MOUSE PRIMORDIAL GERM-CELLS STUDIED BY MIXED AND CLONAL CULTURES

In culture, mouse primordial germ cells (PGCs) proliferate and undergo growth arrest with a time course similar to that in vivo. It is uncle ar whether this behavior is regulated autonomously or by coexisting so matic cells. We performed mixed culture experiments using PGCs from 8. 5- and 11.5-d.p.c. embryos and found no interaction between the PGCs a nd somatic cells at the two stages. Next, we carried out clonal cultur e of PGCs and examined the proliferation of and morphological change i n individual clones, Such clonal culture did not reveal any subpopulat ion of PGCs with an increased growth rate or less differentiated chara cteristics, which might have been suggested by formation of the embryo nic germ cell lines. Our results suggest that there is an autonomous r egulation of growth and cell shape change in PGCs which occur as stoch astical events but are not strictly timed by the number of cell divisi ons. (C) 1996 Academic Press, Inc.