title: The development and anatomy of the gubernaculum in Hoxa11 knockout mice.
abstract: BACKGROUND
  The gubernaculum is central to testicular descent, with recent evidence suggesting that it elongates to the scrotum like a limb bud. Homeobox (Hox) genes involved in limb bud outgrowth are expressed within the gubernaculum. Mice with homozygous Hoxa11 gene deletions have bilateral cryptorchidism. This study investigated the precise anatomical effects of Hoxa11 mutation on the mouse gubernaculum.
  
  
  METHODS
  The pelvises of postnatal mice (n = 46; days 1-10) with Hoxa11 knockout (n = 19), heterozygotes (n = 11), and wild-type (n = 16) mice were serially sectioned and stained with hematoxylin and eosin. Immunohistochemistry was performed for the presence of desmin.
  
  
  RESULTS
  Hoxa11 mutant mice had intraabdominal cryptorchid testes and highly convoluted vas deferentia. The gubernacular bulbs were abnormal, with no "outgrowth" and persistence of the prenatal "swelling reaction." Desmin immunostaining revealed the lack of undifferentiated mesenchymal cells usually seen as a "swirl" within the bulb and decreased formation of cremaster muscle.
  
  
  CONCLUSIONS
  Hoxa11 may be involved in forming the growth center seen as the "swirl" of mesenchyme within the gubernacular bulb, consistent with these cells being required for gubernacular elongation during testicular descent. Hoxa11 mutations may well contribute to failure of gubernacular migration in boys with cryptorchidism.
authors.affiliation: F Douglas Stephens Surgical Research Laboratory, Murdoch Children's Research Institute, Melbourne, Australia.
authors.forename: Shobhana
authors.initials: S
authors.lastname: Nagraj
authors.forename: Gloria J
authors.initials: GJ
authors.lastname: Seah
authors.forename: Pamela J
authors.initials: PJ
authors.lastname: Farmer
authors.forename: Ben
authors.initials: B
authors.lastname: Davies
authors.forename: Bridget
authors.initials: B
authors.lastname: Southwell
authors.forename: Alfor G
authors.initials: AG
authors.lastname: Lewis
authors.forename: John M
authors.initials: JM
authors.lastname: Hutson
mesh_terms: D000728:Androgens / Q000235:genetics / Q000502:physiology; D000818:Animals; D003456:Cryptorchidism / Q000196:embryology / Q000235:genetics; D004195:Disease Models, Animal; D018507:Gene Expression Regulation, Developmental; D005801:Genes, Homeobox / Q000235:genetics; D005837:Genitalia, Male / Q000033:anatomy & histology / Q000196:embryology; D018398:Homeodomain Proteins / Q000235:genetics / Q000502:physiology*; D006801:Humans; D008297:Male; D008648:Mesoderm / Q000196:embryology / Q000254:growth & development; D051379:Mice; D018345:Mice, Knockout; D008817:Mice, Mutant Strains; D009154:Mutation / Q000235:genetics; D013737:Testis / Q000033:anatomy & histology* / Q000196:embryology* / Q000254:growth & development
chemical_list: D000728:Androgens; D018398:Homeodomain Proteins; C533666:Hoxa11 protein, rat