title: Generation of multi-oocyte follicles in the peripubertal rat ovary: link to the invasive capacity of granulosa cells?
abstract: OBJECTIVE
  To assess the presence and numbers of multi-oocyte follicles (MOFs) in the rat ovary at different stages of postnatal maturation.
  
  
  METHODS
  Animal (rat) study.
  
  
  METHODS
  Research laboratory.
  
  
  METHODS
  Female Wistar rats.
  
  
  METHODS
  Histologic/morphometric analyses in ovaries from infantile, juvenile, pubertal, and adult female rats.
  
  
  METHODS
  Numbers and characteristics of MOFs in rat ovaries at different stages of postnatal maturation.
  
  
  RESULTS
  Female rats displayed low numbers (<5/ovary) of MOFs in the infantile period (postnatal day [PND] 15). The occurrence of MOFs increased sharply by PND-21 and remained at high values (>15/ovary) up to PND-60, to decline thereafter by PND-90. The presence of irregularly shaped and connected adjacent follicles, together with the identification of ruptures at the follicle surface and the occasional invasion of the ovarian stroma by granulosa cells, strongly suggests that the majority of MOFs in peripubertal rats are generated by fusion of adjacent growing follicles.
  
  
  CONCLUSIONS
  A new mechanism for the generation of MOFs linked to the potential invasive capacity of granulosa cells is proposed. The basis for the upsurge in the generation of MOFs during the peripubertal period and whether, as predictable, this phenomenon is applicable to other mammalian species warrant further investigation.
authors.affiliation: Department of Cell Biology, Physiology, and Immunology, University of Córdoba, Córdoba, Spain; CIBER Fisiopatología de la Obesidad y Nutrición, Instituto de Salud Carlos III, Córdoba, Spain; Instituto Maimónides de Investigaciones Biomédicas/Hospital Universitario Reina Sofia, Córdoba, Spain. Electronic address: fi1tesem@uco.es.
authors.forename: Francisco
authors.initials: F
authors.lastname: Gaytán
authors.affiliation: Department of Pathology, University of Córdoba, Córdoba, Spain.
authors.forename: Concepción
authors.initials: C
authors.lastname: Morales
authors.affiliation: Department of Cell Biology, Physiology, and Immunology, University of Córdoba, Córdoba, Spain.
authors.forename: María
authors.initials: M
authors.lastname: Manfredi-Lozano
authors.affiliation: Department of Cell Biology, Physiology, and Immunology, University of Córdoba, Córdoba, Spain; CIBER Fisiopatología de la Obesidad y Nutrición, Instituto de Salud Carlos III, Córdoba, Spain; Instituto Maimónides de Investigaciones Biomédicas/Hospital Universitario Reina Sofia, Córdoba, Spain. Electronic address: fi1tesem@uco.es.
authors.forename: Manuel
authors.initials: M
authors.lastname: Tena-Sempere
mesh_terms: D000367:Age Factors; D000818:Animals; D002448:Cell Adhesion / Q000502:physiology; D002465:Cell Movement / Q000502:physiology*; D005260:Female; D006107:Granulosa Cells / Q000166:cytology / Q000502:physiology*; D009865:Oocytes / Q000502:physiology*; D006080:Ovarian Follicle / Q000166:cytology / Q000502:physiology; D010053:Ovary / Q000166:cytology / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D012741:Sexual Maturation / Q000502:physiology*
keywords: Multi-oocyte follicles; follicle fusion; granulosa cells; ovary