Human ovarian biopsies as a viable source of pre-antral follicles

BACKGROUND Our knowledge of the early pre-antral stage of human folliculogenesis is still poor due to small follicle size and the limited availability of human ovarian tissue. Our aim was to determine the utility of ovarian biopsy for pre-antral follicle research. METHODS Ovarian cortical biopsies were obtained from women (28–46 years old) undergoing elective Caesarean sections or total abdominal hysterectomy/bilateral salpingo-oophorectomy for a variety of benign gynaecological conditions. Follicle isolation and staging was performed according to a well-established protocol, involving enzymatic digestion, isolation using fine needles and image capture analysis software. RNA was also isolated for reverse transcription. RESULTS More than 351 follicles were retrieved from 19 patients and 249 were classifiable into follicle stages: 80 primordial, 53 transitional, 82 primary, 26 secondary and 8 multilaminar. All samples, except two from women aged over 40 years, yielded follicles. The average yield of classifiable follicles/patient was 13. There was an age-related decline in mean follicle numbers/patient (r2 = −0.986). Microgram quantities of complementary DNA per follicle were synthesized. CONCLUSIONS Despite the heterogeneous distribution of follicles throughout the cortex and the significant age-related decline in the numbers of follicles retrieved, biopsy samples of ovarian cortical tissue provide a useful source of pre-antral follicles. This, coupled with the sensitivity of genomic technology, makes this method a viable research approach.