Human follicular oocytes and their maturation in vitro.

To study the maturation of follicular oocytes, germ cells were flushed from visible follicles in the ovaries of 145 oophorectomized patients 17 to 65 years of age. The number of oocytes recovered decreased (P less than 0.05) as patient age increased. More oocytes (P less than 0.05) were recovered from ovaries removed during the proliferative stage of the menstrual cycle than during the secretory stage. Of 776 oocytes obtained, 132 (17%) were examined without incubation. Two had matured in vivo and another possessed two vesicular nuclei. Of 124 oocytes incubated in tissue culture Medium 199 or Ham's F10 supplemented with 10% fetal calf serum, 52 (42%) displayed germinal vesicle breakdown and 39 (31%) progressed to metaphase of the second meiotic division within 42 hours. Neither the stage of the cycle at which ovaries were removed nor the addition of progesterone to the medium had a significant effect on maturation. The rate of maturation peaked with oocytes from women 34 to 39 years of age. Even though more oocytes were recovered from patients 17 to 33 years of age than from patients 34 to 39 years, fewer oocytes obtained from the younger patients appeared to be viable, perhaps because of a greater incidence of ovarian follicle pathology in the youngest group.