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Variation in ovarian follicle density during human fetal development

submitted by ebm6riol 1 year and 9 months ago
To obtain a precise estimate of ovarian follicle density and variation in the number of follicles at several gestational ages during human fetal development. Twelve necropsied ovaries from 9 fetuses (gestational age: 24 to 36 weeks) and 3 neonates (who died within the first hours of life) were studied. Ovaries were fixed with 4 % formaldehyde and embedded in paraffin. Serial, 7 mm thick sections of the ovaries were cut and evaluated at every 5 cuts. Follicles were counted in 1 regions (each measuring 625 μm2) of the ovarian cortex and the number of follicles per mm³ was calculated. The number of follicles per .25 mm² ranged from 1.9 (± 4.8) in a neonate to 34.7 (± 1.6) also in a neonate. Among fetuses, follicle density was lowest at 36 weeks of gestation (11.1 ± 6.2) and highest at 26 weeks (32 ± 8.9). The total number of follicles ranged from 5, at the age of 22 weeks to > 1,, at the age of 39 weeks. Our results show a peak in the number of follicles during intrauterine life at approximately 26 weeks, followed by a rapid reduction in this number before birth, providing a step forward towards the understanding of primordial follicular assembly in humans and, ultimately, the identification of the determinants of reproductive capacity.

Topic: Biology

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