Growth of opossum embryos in vitro during organogenesis.

Opossum embryos, explanted between primitive streak and late fetal stages, were grown in culture for periods of 20-30 H. Many of the explants had a good heartbeat and blood circulation in embryo and yolk sac after 12 h, and a few after 24 h. Growth of the embryos included formation of the neural tube and body flexures, increase in the number of somites, differentiation of the limbs and digits, and development of the amnion and allantois. Embryos explanted during the last day of gestation showed persistent and vigorous body movements in culture, particularly of the forelimbs, head and tongue.