Shai D, Aviel-Ronen S, Spector I, et al. - Researchers aimed at determining mechanisms of primordial follicle (PMF) loss in vivo in human ovaries shortly after alkylating agent (AA) chemotherapy. They conducted a cohort study of 96 women aged 15–39 years who underwent ovarian tissue cryopreservation for fertility preservation. Retrieval of fresh ovarian tissue samples was performed from women treated with AA (n = 24) or non-AA (n = 24) chemotherapy < 6 months after treatment and age-matched untreated women (n = 48). Findings revealed significant loss of PMFs, and significant rise in absolute numbers of growing follicles in AA-treated ovaries compared with untreated control ovaries. An inverse association was noted between the number of growing follicles and time from chemotherapy. Occurrence of follicle activation was observed in vivo in ovaries of patients treated with AA, suggesting a possible contribution of a pathologic mechanism in chemotherapy-induced follicle loss.