[Free amino acids and some enzymes of placental amino acid metabolism at different stages of its development].

There were revealed changes in the content of free amino acids and in the activity of glutamic dehydrogenase, aspartic- and alanine-aminotransferases in the course of development of the placenta in guinea pigs. The greatest values by the indices under study were reached by the 25th--30th days of pregnancy, i.e. by the period of final formation of the placenta. By the 40th day of pregnancy the activity of the enzymes and the content of free amino acids fell, and from the 45th day persisted at a certain stable level up to the occurrence of labour.