['To investigate inhibin A, inhibin B, activin A, and P production by cultured granulosa cells (GCs) and what relationship this hormone production has to fertility.', 'Luteinized GCs from individual follicles were cultured, and inhibin A, inhibin B, activin A, and P production were measured by ELISA at 24 and 72 hours.', 'Research laboratory and university hospital.', 'Fifteen women who undertook an IVF-ICSI program, yielding 58 follicles.', 'Individual follicular aspiration and preparation of GCs for culture.', 'Inhibin A, inhibin B, activin A, and P production; oocyte retrieval; and fertility outcome.', 'Inhibin A, inhibin B, and P continued to be secreted by GCs in vitro, and activin A levels were detected only marginally in 56% of cultures. The rate of production also was dependent on the size of follicle from which the GCs originated but not on oocyte presence or ability to fertilize. Granulosa cell stimulation with hCG had no effect on inhibin A but increased P and decreased inhibin B production.'] Are human granulosa-lutein cell in vitro production of progesterone , inhibin A , inhibin B , and activin A dependent on follicular size and not the presence of the oocyte?