title: [Establishment of cryptorchid infertile models by postnatal injection of estradiol in mice].
abstract: OBJECTIVE
  To investigate the incidence and spermatogenesis of cryptorchid testes induced by postnatal injection of estradiol.
  
  
  METHODS
  Ninety male newborn Balb/C mice were randomly divided into an experimental (n = 60), a solvent control (n = 20) and a normal control group (n = 10). The experimental mice were again assigned to a 4-week, a 6-week, an 8-week, and a 10-week subgroup, and injected subcutaneously with 17-beta estradiol (5 microg/d) from 3 to 28, 3 to 42, 3 to 56 and 3 to 70 days after birth, respectively. The incidence of cryptorchidism and morphological changes of the testes were observed at 2 weeks after drug withdrawal.
  
  
  RESULTS
  The incidence rates of cryptorchidism in the 4-, 6-, 8- and 10-week groups were 0%, 26.7%, 60% and 60%, respectively, but no cryptorchidism occurred in the solvent and normal control groups. The 4- and 6-week groups showed autonomous descent of the cryptorchid testes and recovery of spermatogenesis after drug withdrawal. The models became stable and no spermatogenesis recovery was observed after 8 weeks of continuous medication.
  
  
  CONCLUSIONS
  Stable cryptorchid infertile models can be established in mice by postnatally continuous injection of estradiol for over 8 weeks.
authors.affiliation: Department of Urology, The First People's Hospital of Shangqiu, Shangqiu, Henan 476100, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Zhu
authors.forename: Chen
authors.initials: C
authors.lastname: Bai
authors.forename: Yao-Mei
authors.initials: YM
authors.lastname: Yuan
authors.forename: Ci
authors.initials: C
authors.lastname: Zhang
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D003456:Cryptorchidism / Q000139:chemically induced*; D004195:Disease Models, Animal; D004958:Estradiol / Q000009:adverse effects*; D007248:Infertility, Male / Q000139:chemically induced*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C
chemical_list: D004958:Estradiol