GROWTH OF POSTIMPLANTATION MOUSE EMBRYOS CULTURED IN A SERUM-SUPPLEMENTED, CHEMICALLY DEFINED MEDIUM

The isolated mammalian embryo is a relatively unexploited developmental system for studying early somite stages: the embryonic period of greatest susceptibility to teratogenesis. The mouse embryo offers sufficient advantages for such studies that a short‐term culture procedure was adapted for early postimplantation stages (Witschi stages 14 or 15 corresponding to one to 12 somites). Criteria for growth in vitro demonstrated that quantitative determinations of DNA, RNA and protein content consistently correlated with morphological end points. A medium comprising 20% rat serum in Waymouth's MB 752/1 supported better development and net macromolecular synthesis than did media containing 0, 10 or 100% rat serum. Embryos in the 20% serum‐supplemented medium approximately doubled their nucleic acid and protein contents during 22 hours in culture. This increase corresponds to roughly 60% of the growth of embryos in vivo and should permit biochemical investigations to be made of the early effects of teratogenic treatments. Copyright © 1969 Wiley‐Liss, Inc., A Wiley Company