Establishment of ovarian reserve: a quantitative morphometric study of the developing human ovary.

ABSTRACT

OBJECTIVE: To assess directly the dynamics of the formation of the ovarian reserve in the normal human ovary by evaluating the total number of follicles in developing ovaries when folliculogenesis occurs. DESIGN: Histomorphometry-based follicle counts in complete serial tissue sections. SETTING: Functional Anatomy Research Center, University of Milano. PATIENT(S) Thirteen fetuses, neonates, and one 8-month-old infant. INTERVENTION(S) Fifteen ovaries were completely cut, obtaining serial sections. Ovarian volume, volume fractions, density and total number of follicles per ovary were calculated using quantitative morphometric methods. MAIN OUTCOME MEASURE(S) Age-related dynamics of the establishment of ovarian reserve in human developing ovary at the end of the organogenesis. RESULT(S) The ovarian reserve (100,000 follicles at 15 weeks of postconceptional age) increased progressively to 680,000 follicles at 34 weeks. At 8 months of postnatal age the pool was still about 680,000 primordial follicles. CONCLUSION(S) The consistence of the primordial follicle pool during organogenesis shows an exponential increase until month 8 of prenatal life and it is subsequently maintained without modifications at least until month 8 of postnatal life.