A transient endocrine gland that develops from the postovulatory or atretic follicles and secretes progesterone; it is thought to be related to egg retention[PMID].
corpus luteum of ovary
ovarian corpus luteum
maintains the endometrium in mammals[WP]. A corpus luteum is known in hagfish (100), Squalus (101), and salamander (100) but not lamprey (102). There are no data for Branchiostoma and Ciona, and given that they are multiple spawners, there is no a priori reason to conclude that they lack a corpus luteum