Amino acid requirements in the early post-implantation rat conceptus.

Amino acid analysis has been performed on hydrolysates of embryos/fetuses, visceral yolk sacs and ectoplacental cones/placentae from early post-implantation rat conceptuses. The increments in each amino acid between 10.5 and 11.5 days, between 11.5 and 12.5 days, and between 12.5 and 13.5 days, are expressed as percentages of the total amino acid increment. These three profiles are very similar to each other and also strongly resemble the amino acid composition of hydrolysates of rat serum. The results are discussed in the context of the hypothesis that a transudate of plasma is responsible for the amino acid nutrition of the embryo at this stage of gestation, and that inhibition of this pathway can lead to the induction of congenital defects. The results suggest that an inhibition of pinocytosis or lysosomal proteolysis would affect the supply of all protein-derived amino acids to approximately the same extent: there is no indication that the supply of any particular amino acid would be particularly vulnerable.