According to the text, the placenta facilitates the supply of oxygen and nutrients to the embryo and the removal of carbon dioxide and excretory waste materials . It also acts as an endocrine tissue, producing hormones like hCG, hPL, estrogens, and progestogens . However, oxytocin is released from the maternal pituitary gland, triggered by the foetal ejection reflex (signals originating from the foetus and placenta), rather than being secreted by the placenta itself .