FOLLICULAR WALL MAINTAINS MEIOTIC ARREST IN BOVINE OOCYTES CULTURED IN-VITRO

Cumulus oocyte complexes (COCs) were cocultured with parts of the foll icular wall. Coculture conditions were such that the COCs were 1) in c ontinuous contact with the follicular wall (FWC), 2) separated from th e follicular wall at collection but in contact with it during culture (FWR), and 3) separated from the follicular wall, but cultured in its vicinity (FWNR). Oocytes cultured for 24 hr under FWC conditions maint ained the germinal vesicle stage. Under FWR conditions the germinal ve sicle stage was not maintained, but an arrest at metaphase I of meiosi s occurred in mostof the oocytes. When COCs were cultured in the vicin ity of the follicular wall (FWNR), meiosis was resumed and similar num bers of oocytes progressed to metaphase II of meiosis as compared to c ultures of COCs without coculture with parts of the follicular wall. W hen COCs were isolated from the follicular wall after 24 hr of culture and additionally cultured for another 24 hr, the oocytes showed the s ame capability of resuming meiosis as fresh, isolated cumulus oocyte c omplexes. It is concluded that maintenance of contact with the follicu lar wall is necessary to maintain meiotic arrest. When COCs restore a physical contact with the follicular wall during culture, an arrest at metaphase I occurs. (C) 1994 Wiley-Liss, Inc.