人绒毛膜促性腺激素与胚胎种植

Human chorionic gonadotropin and implantation

人绒毛膜促性腺激素（HCG）是一种由早期胚胎滋养球细胞和胎盘滋养层合体细胞分泌的、两个亚基以非共价健结合的糖蛋白激素。目前认为它是滋养层细胞和众多胚胎源性物质中最早出现的标志物。

Human chorionic gonadotropin（HCG）is a glycoprotein hormone comprised of 2 subunits a and b that are noncovalently joined. HCG is primarily produced by the embryo and later by the syncytiotrophoblast. HCG has been detected at variable levels both in pre-implantation embryo culture media in vitro and in women serum after fertilization around implantation period or early pregnancy. HCG is not only considered to assess embryo competence both in anatomic and biochemical, but also contributes to improve luteal function and endometrial modification or placenta construction for supporting early pregnancy.