Chiarella Sforza1, Laura Vizzotto, Virgilio F Ferrario, Antonino Forabosco. 1. Functional Anatomy Research Center, Dipartimento di Anatomia Umana, Facoltà di Medicina e Chirurgia and Facoltà di Scienze Motorie, Università degli Studi di Milano, via Mangiagalli 31, Milan 20133, Italy. farc@unimi.it
Abstract
BACKGROUND: Follicular growth in the mammalian ovary follows a geographically determined pattern, but no exhaustive data about their spatial localization in the cortex of human ovary exists. AIM: The aim of this study is to assess the spatial position of the follicles during human ovarian definitive histogenesis using morphometric methods. SUBJECTS: Ovaries removed from four fetuses, five newborns and one 8-month-old child with 46,XX karyotype was used. OUTCOME MEASURES: The position of the different follicle categories (primordial, primary, secondary and antral) was estimated as percentage distance of the centroid of the follicle from the cortico-medullary boundary. RESULTS: In normal ovaries, during definitive histogenesis, the primordial follicles progressively occupy more peripheral parts of the cortex (on average, 41% of cortical length at 20 weeks of fetal development, 53% at birth, 68% at 8 postnatal months). Primary follicles were crowded in the inner part of the cortex (newborn: 30-40% of cortical length; 8 months: 52% of cortical length). Secondary and antral follicles were sampled in all neonatal specimens and in the 8-month old specimen; they were grouped next to the cortico-medullary boundary. CONCLUSIONS: Ovarian development corresponded to a migration of the maximum crowding of follicles from a position next to the medulla towards a more peripheral location. The control of the primordial follicle assembly, recruitment and development are coordinated by locally produced paracrine factors. The action of these factors seems to follow a negative gradient from the cortex toward the medulla.
BACKGROUND: Follicular growth in the mammalian ovary follows a geographically determined pattern, but no exhaustive data about their spatial localization in the cortex of human ovary exists. AIM: The aim of this study is to assess the spatial position of the follicles during human ovarian definitive histogenesis using morphometric methods. SUBJECTS: Ovaries removed from four fetuses, five newborns and one 8-month-old child with 46,XX karyotype was used. OUTCOME MEASURES: The position of the different follicle categories (primordial, primary, secondary and antral) was estimated as percentage distance of the centroid of the follicle from the cortico-medullary boundary. RESULTS: In normal ovaries, during definitive histogenesis, the primordial follicles progressively occupy more peripheral parts of the cortex (on average, 41% of cortical length at 20 weeks of fetal development, 53% at birth, 68% at 8 postnatal months). Primary follicles were crowded in the inner part of the cortex (newborn: 30-40% of cortical length; 8 months: 52% of cortical length). Secondary and antral follicles were sampled in all neonatal specimens and in the 8-month old specimen; they were grouped next to the cortico-medullary boundary. CONCLUSIONS: Ovarian development corresponded to a migration of the maximum crowding of follicles from a position next to the medulla towards a more peripheral location. The control of the primordial follicle assembly, recruitment and development are coordinated by locally produced paracrine factors. The action of these factors seems to follow a negative gradient from the cortex toward the medulla.
Authors: Richard A Anderson; Luke McIlwain; Shiona Coutts; Hazel L Kinnell; Paul A Fowler; Andrew J Childs Journal: Mol Hum Reprod Date: 2013-08-26 Impact factor: 4.025