Differentiation In Vitro of Normal Mouse Embryos and Mouse Embryonal Carcinoma2

Abstract

Mouse embryos differentiated in vitro to the early somite stage, with blood circulation and heartbeat equivalent to normal 9-day mouse embryos. Embryoid bodies differentiated in vitro in the same medium. The disorganized embryonal carcinoma in the core of the embryoid body became well organized and formed rosettes, with the long axis of the cells perpendicular to the center of the cavity. The embryoid body, proliferated by budding, formed up to 30 polycysts, each with an inner core of relatively well-organized ectoderm and L-cell layer of endoderm around it. Mesoderm later differentiated between the endoderm and ectoderm. Some embryoid bodies developed yolk sac with blood islands containing primary red blood cells. Other embryoid bodies developed nodules of squamous cell epithelium enclosing a keratin substance in the core. Neither squamous cell epithelium nor keratin substance was observed in normal embryos that differentiated in vitro.