The relationship of human granulosa-lutein cell proliferative index to follicular diameter and serum estradiol

OBJECTIVE: To examine the relationships of follicular diameter and serum estradiol (E2) to the percentage of granulosa cells undergoing mitosis as reflected by the proliferative index of granulosa cells. METHODS: In this prospective study, we enrolled 44 consecutive women undergoing controlled ovarian hyperstimulation for in vitro fertilization. Deoxyribonucleic acid histograms were generated by flow cytometry from granulosa cells isolated at the time of transvaginal aspiration. Proliferative index was defined as the sum of G2/M and S phases. We assessed the correlation between proliferative index and age, maximum serum E2, number of oocytes retrieved, percent mature oocytes, and follicular diameter. RESULTS: Follicles less than 16 mm had a significantly higher proliferative index (19.9 +/- 3.3%) than follicles 20 mm or greater (14.8 +/- 3.9%, P = .016). However, there was no significant difference between proliferative index of the latter group and proliferative index of follicles 16-19 mm (17.8 +/- 4.7%). An inverse correlation between patient age and proliferative index of granulosa cells was noted (r = -.39, P = .018). There was no significant relationship between serum E2 and proliferative index (P = .97). CONCLUSION: Mitotic activity tends to decrease as follicular diameter increases after a threshold diameter is achieved. Proliferative index of granulosa cells provides insight into the underlying cell biology of a follicle.