Accumulation of DNA, RNA, and protein by cultured rat embryos following maternal administration of a teratogenic dose of trypan blue.

The effect of trypan blue on the rates of DNA, RNA, and protein accumulation in rat embryos was investigated using a system of whole embryo culture. Embryos were isolated on the 10th gestational day (sperm day = Day 0) either 4 or 24 hr after maternal injection. The cultivation period was for 24 or 42 hr. The rate of DNA and RNA accumulation in the embryo following either a 4- or 24-hr previous maternal treatment was significantly decreased at at both 24 and 42 hr of cultivation. Protein values were significantly reduced after a 4-hr maternal exposure, but only slightly reduced after a 24-hr maternal exposure. No significant differences in DNA, RNA, or protein content were observed at the beginning of cultivation, following either a 4- or 24-hr previous maternal treatment. The percentage of embryos establishing a visceral yolk sac circulation was greatly reduced, and this supports the conclusion that trypan blue interferes with yolk sac function. The most obvious teratogenic insults include failure of neuropore closure, retention of a dorsiflexed position, and cranial edema.