Within the ovary, required for the organization of somatic cells and oocytes into discrete follicular structures. Binds 2 Zn(2+) ions per subunit. Widely expressed, with highest levels in ovary, kidney, hypothalamus and hippocampus. Within the ovarian follicle, expressed in granulosa cells, but not in oocytes. Present in both preantral and antral follicles, but not in atretic antral follicle. Increasing expression in the ovary between fetal day 21 and postnatal day 2. Expression decreases thereafter to lower levels in adult ovaries. Belongs to the peptidase M28 family.