P-417 Biovular follicles are commonly found in prepubertal but not adult ovaries

Abstract Study question Is the morphology of ovarian tissue from paediatric and adolescent girls similar to that adults? Summary answer The presence biovular follicles was more frequently observed in ovary than adult ovary. What is known already At birth there are approximately 1 million reduce around 380,000 by puberty. Limited information available on but it thought that, before age 6 years, prepubertal contains 20% abnormal primordial - Polyovular common some animal species rarely human They contribute dizygotic twinning low frequency suggests they not sole origin. design, size, duration Haematoxylin eosin stained sections were examined 2 operators blinded patient age. Follicles classified according modified Gougeon criteria. proportions compared with Fisher’s exact test one- way ANOVA. Participants/materials, setting, methods Ovarian cortex collected a total 71 children adolescents 85 adults undergoing fertility preservation. Those who had previous chemotherapy or pelvic irradiation excluded. population divided into 30 (<8 range 7.6 years), 25 peripubertal (8 14.1 16 confirmed pubertal status (13.7 16.6 years) (18-36 years). Main results role chance Biovular 36.7% (11/30) <8 years with, where present, an average 1/10.6 x103 follicles, 28% (7/25) 1/11.9x103 18.7% (3/16) post 1/7.7x103 follicles. In contrast, seen (3.5%, 3/85) 1/25x103 all younger samples significantly different (p < 0.001 p peripubertal, 0.05 pubertal) between young groups. those any An antral follicle only one case (1.4 3.3%, (8%), 4 (25%) 9 cases (10.6%). higher year 0.05). Limitations, reasons for caution Only small sample each individual, which may be representative adult. It possible predict potential function this analysis. Wider implications findings Although numbers high, structural anomalies such as also appears changes at puberty cause loss these Trial registration number Not Applicable