Rat conceptus development in vitro: Comparative effects of alkylating agents

Abstract

Conceptuses removed from the rats in the eleventh day of gestation were cultured in vitro for 2 days. Growth and differentiation of the major organs of the embryo in vitro resembled those developed in vivo. Embryonic development and organogenesis were markedly affected when the alkylating agents TEM (2,4,6-triethylenimino-1,3,5-triazine) and nitrogen mustard (mechlorethamine hydrochloride) were added to the culture medium. At concentrations of 1 and 5 μg/ml medium, these teratogens were highly embryotoxic and affected both growth and differentiation. DNA and protein content of embryos and yolk sacs was reduced significantly ( p < 0.001) from the controls. Development of conceptuses in the culture medium that contained cyclophosphamide (0.35 m m) alone apparently were normal. However, addition of cyclophosphamide (0.35 m m), microsomes (0.5 mg protein/ml), and NADPH (1 m m) to the culture medium induced marked deleterious effects on the conceptus growth and differentiation. DNA and protein contents were significantly ( p < 0.001) reduced by the combined treatment indicative of formation of reactive metabolites and their interference with macro-molecular biosynthesis. Aminopyrine which has not been shown to be teratogenic, in equimolar amounts to cyclophosphamide, under identical conditions of culture, did not affect conceptus development.