Proliferation and apoptosis of fibroblasts and smooth muscle cells in rat uterine cervix throughout gestation and the effect of the antiprogesterone onapristone

OBJECTIVE: The purpose of this study was to determine the relative percentages of apoptosis and proliferation in fibroblasts and cervical smooth muscles throughout gestation and the effect of an antiprogesterone on these processes. STUDY DESIGN: Rats were studied at days 5, 15, 18, and 21 and immediately postpartum (day 22). Apoptosis and proliferation as detected by specific immunohistochemistry quantitative morphometric analysis was performed. Onapristone, an antiprogesterone, was used to study effects of hormonal change on these processes in 16- and 19-day timed-pregnant rats. RESULTS: Proliferation of fibroblasts and smooth muscle cells was highest in early pregnancy and decreased progressively, whereas apoptosis increased progressively in later pregnancy. Onapristone inhibited apoptosis. CONCLUSION: Changes in cervical cellular turnover are initiated early in gestation and are under hormonal influence. Antiprogesterone inhibits cell death at days 16 and 19 of gestation.