The uterine glands open between the microcotyledons, into the spaces between the chorionic and uterine epithelium. These spaces thus become a continuous network of __*__-filled channels or arcades involving the entire placenta (the arcades are homologous to the areolae seen in other species). No microcotyledons are formed opposite the endometrial cups, which later form cup-like indentations due to the accumulation of __*__.