Successful Development and Birth of Mice cultivated in vitro as Early Embryos

EXPERIMENTAL embryology in mammals is hampered by the comparative inaccessibility of the mammalian embryo. The development of techniques for the cultivation in vitro of early mammalian embryos has provided one possible route for experimental interference in the course of embryonic development, through alteration in the conditions of culture and the composition of the culture medium. However, a study of the effects of such experimental interference upon later embryonic development also requires the application of techniques for transplanting early embryos to foster mothers. The first successful attempt to combine the techniques of embryo culture and embryo transplantation was briefly reported by Adams¹. 16-cell rabbit embryos were incubated for 21½ hr. in Krebs-Ringer bicarbonate containing 2 mgm./ml. bovine plasma albumin, fraction V (Armour), during which time cleavage continued at the normal rate. They were then transferred to a recipient female mated 3 days previously to a vasectomized male. One week later there were normal embryos in the uterus of the recipient female, presumably developed from the cultured embryos.