Preliminary studies on apoptosis in human fetal ovaries

Objective: To evaluate if apoptosis occurs in human germ cells between 19 and 33 gestational weeks (GW). Design: Human fetal ovaries were obtained from aborted fetuses aged 19-33 GW. Setting: Rabin Medical Center, a major tertiary care and referral center. Patient(s): Twenty-seven women undergoing pregnancy termination. The abortions were mostly because of fetal anatomical or chromosomal abnormalities. Intervention(s): None. Main Outcome Measure(s): Microscopy studies, terminal deoxynucleotidyl transferase (TdT) assay (TUNEL), and immunocytochemistry for B-cell lymphoma/leukemia-2 (bcl-2). Result(s): TUNEL assay revealed a slight increase in apoptotic oocytes in fetuses from 23 GW, with a peak at 27 GW. Overexpression of bcl-2 was detected in all ovarian components, regardless of fetal age. Conclusion(s): There seems to be a slight increase in apoptosis in oocytes from 23 GW with a peak at 27 GW. However, it is very unlikely that these low apoptotic rates could be the cause of the extensive germ cell loss throughout human pregnancy. The overexpression of bcl-2 possibly suggests either that this gene is necessary to overcome extensive apoptotic activity or that it is responsible for the low apoptosis rates. However, these results should be considered with caution, since the ovaries were mostly from abnormal fetuses after feticide.