Ontogenesis of immunoreactive growth hormone, follicle-stimulating hormone, thyroid-stimulating hormine, luteinizing hormone, chorionic prolactin and chorionic gonadotropin in the human conceptus.

Abstract

The synthesis of immunoreactive growth hormone, follicle-stimulating hormone, thyroid-stimulating hormone and luteinizing hormone in 11 embryos and fetuses of 29 days' to 18.0 weeks' gestation was investigated by incubating selected tissues in 14C-labeled amino acids, followed by immunoelectrophoresis of the concentrated culture fluids and radioautography. Synthesis of growth hormone was first evident at 9.0 weeks' gestation; the radioactive hormone found in the pituitary cultures yielded labeled peptides on α-chymotryptic hydrolysis which matched the peptides in α-chymotryptic hydrolysates of unlabeled purified growth hormone. Synthesis of thyroid-stimulating hormone was first observed at 14.0 weeks' gestation, at which time synthesis of follicle-stimulating hormone was well established. Study of luteinizing hormone synthesis was complicated by the synthesis of a labeled substance in most of the cultures which was probably not the hormone but which was precipitable with antisera against luteinizing hormone. The synthesis of chorionic growth hormone-prolactin and the synthesis of chorionic gonadotropin were similarly studied by incubation of placental tissue in labeled amino acids, immunoelectrophoresis and radioautography. Synthesis of both hormones was evident as early as 29 days' gestation, the earliest stage studied. Synthesis of chorionic prolactin was approximately constant per unit weight of placenta from 29 days' to 18 weeks' gestation, the period studied, while the synthesis of chorionic gonadotropin was greater in those placentas from the first trimester.