Modification and standardization of the culture of early postimplantation embryos for toxicological studies.

The method of culturing "whole" rat embryos (days 9.5-11.5 of gestation, i.e. at the early stage of organogenesis) as modified and standardized in our laboratory is presented; We have succeeded in using bovine serum as culture medium instead of rat serum as recommended in the original procedure. Experimental conditions are described for obtaining reproducible results; An improved scoring system was developed which, in connection with a computerized documentation, greatly facilitates the evaluation of the data.