Representative micrographs from the ovary of immature rats primed with eCG at 21 (A) or 23 (B) days of age, showing luteinized follicles ruptured at the apex. The ovarian surface epithelium (OSE, arrows in A and B), and its basement membrane (arrowheads in B) remain intact, whereas the underlying ovarian tissue has been degraded (asterisk in A). The COC is retained under the ovarian surface. OB, ovarian bursa. Hematoxylin and eosin.