According to the text, the placenta acts as an endocrine tissue and produces several hormones like human chorionic gonadotropin (hCG), human placental lactogen (hPL), estrogens, and progestogens (progesterone). The text clarifies that while relaxin is secreted during pregnancy, it is secreted by the ovary. Oxytocin and prolactin are pituitary hormones, and glucocorticoids are adrenal hormones.