title: Role of the neonatal period of pituitary-testicular activity in germ cell proliferation and differentiation in the primate testis.
abstract: BACKGROUND
  The neonatal period of pituitary-testicular activity (NPTA) in human males has been hypothesized to play a role in germ cell proliferation and differentiation and to be defective in cryptorchid testes. The present study was carried out to establish in the marmoset if suppression of the NPTA, by treatment with a GnRH antagonist, results in impaired germ cell proliferation and/or differentiation.
  
  
  METHODS
  Comparison of germ cell (GC) numbers and differentiation from gonocytes to pre-spermatogonia and spermatogonia, at birth (in controls) and at the end of the NPTA in marmoset co-twin males treated from birth to age 14 weeks with vehicle or GnRH antagonist.
  
  
  RESULTS
  From birth to age 18-24 weeks, testis weight increased approximately 5-fold and GC number approximately 10-fold, including increased numbers of gonocytes and pre-spermatogonia and the first appearance of spermatogonia. Treatment with GnRH antagonist attenuated the increase in testis weight and GC numbers, but the effect was only partial (24-30% reduction), and the relative proportions of gonocytes, pre-spermatogonia and spermatogonia in the GnRH antagonist-treated group were unchanged from control values.
  
  
  CONCLUSIONS
  The NPTA plays only a minor, if any, role in GC proliferation and differentiation in the marmoset. The changes in GnRH antagonist-treated co-twins may reflect impaired GC survival due to withdrawal of gonadotrophin support for Sertoli cells. These findings do not support a pivotal role for the NPTA in neonatal GC development in primates.
mesh_terms: D000818:Animals; D000831:Animals, Newborn / Q000254:growth & development / Q000502:physiology*; D002144:Callithrix / Q000502:physiology*; D002454:Cell Differentiation / Q000502:physiology; D002455:Cell Division / Q000502:physiology; D016922:Cellular Senescence / Q000187:drug effects; D007987:Gonadotropin-Releasing Hormone / Q000037:antagonists & inhibitors; D008297:Male; D010902:Pituitary Gland / Q000187:drug effects / Q000502:physiology*; D013093:Spermatogonia / Q000166:cytology / Q000502:physiology; D013094:Spermatozoa / Q000166:cytology* / Q000502:physiology; D013737:Testis / Q000187:drug effects / Q000254:growth & development / Q000502:physiology*; D014427:Twins
chemical_list: D007987:Gonadotropin-Releasing Hormone