No abstract

Summary. Selected tissues from human embryos of 6 to 9 weeks' gestation, from rat fetuses of 15 days' gestation, and from rats 2 days of age were incubated with 14C-labeled amino acids. Immunoelectrophoresis of the culture fluid after incubation, using rabbit antisera against human and rat fetal serum proteins, followed by radioautography revealed that: 1) Radioactive a-fetoprotein was present in cultures of human liver, rat liver, and rat yolk sac, but not in cultures of human or rat brain, lung, heart, kidney, intestines, skeletal muscle, skin, or placenta; human yolk sac was not studied. 2) Radioactive transferrin was also present in rat yolk sac cultures, and the same protein was found in rat liver cultures as well. 3) Rat liver and rat placenta cultures both produced radioactive serum Ra2-globulin.Serum a-fetoprotein concentrations in the rat declined abruptly after birth to approximately half of the prenatal level by 2 to 3 days of age, in accord with the loss of the fetal membranes at delivery; the a-fetoprotein level then remained relatively constant until the rat was 6 to 8 days of age, after which synthesis of the protein was increasingly suppressed. IntroductionAt some time before the seventh week of gestation, an a-globulin, which has been termed a-fetoprotein, appears in the serum of the human embryo (1). Synthesis of the protein increases rapidly, and by 13 weeks' gestation serum concentrations of approximately 300 mg per 100 ml are attained. The total amount of serum a-fetoprotein synthesized by the conceptus continues to increase until 20 weeks' gestation, but the serum concentration of the protein decreases after the thirteenth week, due to a rate of fetal growth greater than the rela--tive increase in the amount of a-fetoprotein synthesized. After 20 weeks' gestation, total a-fetoprotein synthesis becomes relatively constant until

No abstract

No abstract