hCG is secreted primarily by the

Syncytiotrophoblast is the epithelial covering of the highly vascular embryonic chorionic villi, which invades the wall of the uterus to establish nutrient circulation between the embryo and the mother. The syncytiotrophoblast secretes human chorionic gonadotropin (hCG). hCG prevents degeneration of the corpus luteum, as progesteron secreted by corpus luteum is vitam in maintaining the pregnancy.