Maturation and fertilization of morphologically immature human oocytes in a program of in vitro fertilization.

Oocytes of varying stages of maturity were aspirated from follicles primed with either human menopausal gonadotropin (hMG) and human chorionic gonadotropin (hCG) or a combination of follicle-stimulating hormone (FSH), hMG and hCG. Of the aspirated oocytes from 44 cycles, 74 were considered to be immature by virtue of morphologic characteristics of the oocytes and the degree of intercellular expansion of the associated cumular and membrana granulosa cells. After incubation periods of 22 to 35 hours in a Ham's F-10-based culture medium, these immature oocytes were inseminated with sperm donated by the patient's husband. Ultimately, 44 conceptuses were transferred to the respective uteri of 30 patients. Eight pregnancies were established as a result of these 30 transfers, two of which resulted from the transfer of only developed immature oocytes.