Age-Associated Primordial Follicle Density in Human Ovarian Cortical Tissue from Post-Pubertal Females Undergoing Ovarian Tissue Cryopreservation and Transplantation: A Descriptive Analysis

OBJECTIVE: To describe the age-associated distribution of primordial follicle density (PFD) in human ovarian cortical tissue from post-pubertal individuals undergoing ovarian tissue cryopreservation, with observations concentrated in the 20-34-year range. DESIGN: Descriptive translational research study using log-transformed quantile regression to characterize conditional percentiles of PFD, with bootstrap resampling to assess uncertainty. SUBJECTS: Ovarian cortical tissue from 33 post-pubertal individuals aged 16-43 years obtained from organ donors and patients undergoing ovarian tissue cryopreservation, without prior exposure to intensive alkylating agent-based chemotherapy. EXPOSURE: Age at ovarian tissue harvesting. MAIN OUTCOME MEASURES: Age-specific distribution of PFD (follicles/mm²), modeled across the 10th, 25th, 50th, 75th, and 90th percentiles; estimates outside the 20-34-year range are exploratory owing to sparse representation. RESULTS: Primordial follicle density declined nonlinearly with age, with wide interindividual variability. Within the well-represented 20-34-year range (21 of 33 individuals), the estimated median PFD decreased from 1.18 follicles/mm² at age 20 to 0.49 follicles/mm² at age 34. Estimates at younger (16-19 years, n=2) and older (35-43 years, n=10) ages showed substantially wider bootstrap uncertainty and should be considered exploratory. An exploratory descriptive analysis of PFD and graft duration among eight ovarian transplant recipients was also performed. CONCLUSION: This study provides a descriptive characterization of the age-associated distribution of PFD in ovarian cortical tissue prepared under contemporary fertility-preservation conditions. These findings are concentrated in the 20-34-year range and are hypothesis-generating. Larger multicenter studies linking PFD to graft function and longevity are needed before age-specific percentiles can inform individualized ovarian tissue transplantation.