Final answer:
The hormone produced early in pregnancy by the embryo is HCG, not FSH, LH, or ADH. FSH and LH are pituitary hormones that control reproductive functions and are regulated by GnRH from the hypothalamus.
Step-by-step explanation:
The hormone produced by the embryo early in pregnancy is human chorionic gonadotropin (HCG). This hormone is critical for maintaining the corpus luteum and supporting the endometrial lining of the uterus during the early stages of pregnancy. It can be detected in pregnancy tests and is also responsible for signaling the body that an embryo is present.
Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) are produced by the pituitary gland and play essential roles in the reproductive system, regulating the menstrual cycle and stimulating the gonads in both sexes. LH and FSH release from the anterior pituitary is stimulated by gonadotropin-releasing hormone (GnRH), which is secreted by the hypothalamus. After ovulation, the corpus luteum is formed and it starts to secrete progesterone, which helps in thickening the endometrium.
The secretion of these hormones is tightly regulated through a feedback mechanism involving hormones like estrogen and progesterone produced by the ovaries, and GnRH from the hypothalamus.