title: Successful long-term preservation of rat sperm by freeze-drying.
abstract: BACKGROUND
  Freeze-drying sperm has been developed as a new preservation method where liquid nitrogen is no longer necessary. An advantage of freeze-drying sperm is that it can be stored at 4 °C and transported at room temperature. Although the successful freeze-drying of sperm has been reported in a number of animals, the possibility of long-term preservation using this method has not yet been studied.
  
  
  RESULTS
  Offspring were obtained from oocytes fertilized with rat epididymal sperm freeze-dried using a solution containing 10 mM Tris and 1 mM EDTA adjusted to pH 8.0. Tolerance of testicular sperm to freeze-drying was increased by pre-treatment with diamide. Offspring with normal fertility were obtained from oocytes fertilized with freeze-dried epididymal sperm stored at 4 °C for 5 years.
  
  
  CONCLUSIONS
  Sperm with -SS- cross-linking in the thiol-disulfide of their protamine were highly tolerant to freeze-drying, and the fertility of freeze-dried sperm was maintained for 5 years without deterioration. This is the first report to demonstrate the successful freeze-drying of sperm using a new and simple method for long-term preservation.
authors.affiliation: Institute of Laboratory Animals, Graduate School of Medicine, Kyoto University, Kyoto, Japan. tkaneko@anim.med.kyoto-u.ac.jp
authors.forename: Takehito
authors.initials: T
authors.lastname: Kaneko
authors.forename: Tadao
authors.initials: T
authors.lastname: Serikawa
mesh_terms: D000818:Animals; D015925:Cryopreservation / Q000379:methods; D003958:Diamide / Q000008:administration & dosage; D004492:Edetic Acid / Q000008:administration & dosage; D005260:Female; D005298:Fertility; D005612:Freeze Drying; D008297:Male; D051381:Rats; D012662:Semen Preservation / Q000379:methods*; D014325:Tromethamine / Q000008:administration & dosage
chemical_list: D014325:Tromethamine; D003958:Diamide; D004492:Edetic Acid