title: Is matrix metalloproteinase required in postnatal testicular tubules for germ cell maturation?
abstract: OBJECTIVE
  Cryptorchidism may cause infertility by failed transformation of neonatal gonocytes into adult dark spermatogonia, the putative stem cells for spermatogenesis. Gonocytes migrate centrifugally to the tubular basement membrane to become adult dark spermatogonia. Regulation of this transformation remains unknown. We aimed to investigate neonatal rodent testis matrix metalloproteinase (MMP) production to see whether MMPs loosen extracellular matrix between Sertoli cells to facilitate gonocyte movement.
  
  
  METHODS
  Sprague-Dawley rat testes (n = 4-6 per group) were collected at embryonic day 19 (E19) and postnatal (P) days P0 to 10 for immunohistochemistry. Immunofluorescent confocal images were captured for presence of membrane type 1 MMP (MT1-MMP), matrix metalloproteinase 2 (MMP2), tissue inhibitor of metalloproteinase 2 (TIMP2), mouse VASA homologue, anti-Müllerian hormone, and androgen receptor in tissue sections. Testicular proteins were analyzed by immunoblotting.
  
  
  RESULTS
  Membrane type 1 MMP was strongly present in gonocytes at E19 then decreased, whereas it increased in testicular somatic cells from P0 to P10. Testicular protein levels of MT1-MMP, MMP2, and androgen receptor were constant from E19 to P10. Anti-Müllerian hormone protein sharply decreased after P2, whereas TIMP2 gradually increased from E19 to P10. Gonocytes migrated to basement membrane at P2 to P6.
  
  
  CONCLUSIONS
  Membrane type 1 MMP, MMP2, and TIMP2 were present in testis from E19 to P10 during gonocyte migration and transformation into spermatogenic stem cells. Increased knowledge about germ cell development may aid efforts to improve fertility in cryptorchidism.
authors.affiliation: F. Douglas Stephens Surgical Research Laboratory, Murdoch Childrens Research Institute, Melbourne 3052, Australia.
authors.forename: Ruili
authors.initials: R
authors.lastname: Li
authors.forename: Jian-Guo
authors.initials: JG
authors.lastname: Zhang
authors.forename: James
authors.initials: J
authors.lastname: Churchill
authors.forename: Magdy
authors.initials: M
authors.lastname: Sourial
authors.forename: Bridget R
authors.initials: BR
authors.lastname: Southwell
authors.forename: John M
authors.initials: JM
authors.lastname: Hutson
mesh_terms: D000818:Animals; D054304:Anti-Mullerian Hormone / Q000378:metabolism; D015415:Biomarkers / Q000378:metabolism; D002465:Cell Movement; D053487:DEAD-box RNA Helicases / Q000378:metabolism; D005109:Extracellular Matrix / Q000502:physiology; D015151:Immunoblotting; D008297:Male; D053511:Matrix Metalloproteinase 14 / Q000378:metabolism*; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism*; D018613:Microscopy, Confocal; D051381:Rats; D017207:Rats, Sprague-Dawley; D011944:Receptors, Androgen / Q000378:metabolism; D013091:Spermatogenesis / Q000502:physiology*; D013093:Spermatogonia / Q000502:physiology*; D013737:Testis / Q000196:embryology / Q000378:metabolism* / Q000502:physiology; D019716:Tissue Inhibitor of Metalloproteinase-2 / Q000378:metabolism*
chemical_list: D015415:Biomarkers; D011944:Receptors, Androgen; D019716:Tissue Inhibitor of Metalloproteinase-2; D054304:Anti-Mullerian Hormone; D020778:Matrix Metalloproteinase 2; C522363:Mmp2 protein, rat; D053511:Matrix Metalloproteinase 14; D053487:DEAD-box RNA Helicases