Application of post-implantation embryo culture to problems in teratology

Rat embryos explanted at 9 1/2 or 11 1/2 days of gestation and cultured in rotating bottles were subjected to a number of agents. Embryos explanted at 9 1/2 days (head-fold stage) and incubated for 48 h at 40.5 degrees C were retarded and abnormal and these effects were more severe in embryos cultured at 41 degrees C. Embryos exposed to 40 degrees over this period were superficially normal, but separate head and body protein determinations and careful measurement of the head dimensions showed them to be microcephalic. Addition of 12-15 mg/ml D-glucose to the culture medium of embryos grown in vitro over the same period also produces malformations. This teratogenic action of D-glucose is distinct from but exacerbated by its osmotic effect. Embryos explanted 12 h earlier (i.e. at 9 days of gestation) and cultured for 66 h were more sensitive to excess glucose--abnormalities were produced by 6-9 mg/ml exogenous D-glucose. Embryos explanted at 11 1/2 days of gestation and cultured for 18 h responded to both 10% CO and suboptimal oxygen levels with a reduction in growth rate and an increase in the ratio of lactate produced to glucose consumed, suggesting a shift to less efficient anaerobic energy metabolism.