Developmental potency of mouse primitive ectoderm cells, embryonic ectoderm cells and primordial germ cells after blastocyst injection
Shen Sanbing Institute of Developmental Biology,Academia Sinica, Beijing, China
Developmental potency of primitive and embryonic ectoderm cells from 4.50-day to 6.25-day post-coitum (p.c.) mouse embryos and primordial germ cells from 12.50-day p.c. male genital ridges of fetal mice were studied by direct introducing them into 3.50-day p.c. blastocysts. Sixteen (61.5%) overt chimaeras out of 26(50% ) offsprings were obtained after transfer of 52 blastocysts injected with 4.50-day primitive ectoderm cells; four (16.0% ) overt chimaeras were obtained out of 25 (51.0% ) offsprings with 4.75-day primitive ectoderm cells from 49 transferred blastocysts. However, no overt chimaera was obtained with either 5.25-day or 6.25-day embryonic ectoderm cells or 12.50-day male primordial germ cells. GPI analysis of mid-gestation conceptuses developed from injected blastocysts showed that 5.25-day embryonic ectoderm cells could only contributed to yolk sac of con-ceptus. Results suggested that implantation acts as a trigger for the determination of primitive ectoderm cells, and their developmental potency becomes limited within a short period of time in normal development.