GROWTH-INVITRO AND ACQUISITION OF MEIOTIC COMPETENCE AFTER THE CRYOPRESERVATION OF ISOLATED MOUSE PRIMARY OVARIAN FOLLICLES

The growth and acquisition of meiotic competence of oocytes from fresh and frozen-thawed primary follicles collected from 10-day-old mice was compared during culture in collagen gels for 12 days. The oocytes contained in primary follicles have a mean diameter of about 48-mu-m and do not resume meiosis without further growth and development. During the 12-day culture period the mean diameter of the oocytes increased to over 60-mu-m. The oocytes were capable of resuming meiosis when isolated from the gel and cultured in the absence of follicular cells in a manner similar to that observed in vivo. Freezing and thawing did not affect oocyte growth or the ability to resume meiosis; this demonstrates the possibility of storing large numbers of female gametes for subsequent development.