The placenta is not a permanent gland of the endocrine system but it also has endocrinal function. The placenta produces estrogen and progesterone. It also secretes human chorionic gonadotropin (HCG, that acts similarly to the hypophyseal LH), human placental lactogen, similar to prolactin and stimulant of the mammary glands, and a series of hormonal peptides similar to the hormones of the hypothalamus-hypophysis axis.
