Offspring derived from oocytes injected with rat sperm, frozen or freeze-dried without cryoprotection.
Sperm preservation is a valuable technique for maintaining genetic resources in biomedical research. In the present study, 10mM Tris-HCl and 1mM EDTA (TE buffer; a simple solution without cryoprotection), was used to freeze or freeze-dry rat sperm. The results were compared with rat sperm frozen using a solution containing Equex STM and egg yolk. Sperm from Wistar and Sprague-Dawley (SD) rats were evaluated by injecting them individually into oocytes derived from the same strain. Of the oocytes that survived after sperm injection, more than 94% were fertilized in all treatments of both strains. In the Wistar rat, 27, 20, 43, and 30% of 2-cell embryos developed to blastocysts, and 35, 9, 11, and 14% of 2-cell embryos developed to offspring from oocytes injected with fresh, frozen (Equex STM/egg yolk), frozen (TE buffer), and freeze-dried sperm, respectively. Using the analagous sources of sperm in the SD rat, 45, 14, 27, and 7% of 2-cell embryos developed to blastocysts, and 22, 0, 14, and 4% of 2-cell embryos developed to offspring. These results demonstrated that rat sperm could be frozen or freeze-dried using TE buffer. We concluded that this simple preservation method, in which cryoprotection was not required, allowed sperm to be preserved efficiently with maintenance of their fertilizing ability.
Kaneko
T
T
Division of Reproductive Engineering, Center for Animal Resources and Development (CARD), Kumamoto University, 2-2-1 Honjo, Kumamoto, Japan. take@kumamoto-u.ac.jp
Kimura
S
S
Nakagata
N
N
D000818:Animals; D015925:Cryopreservation / Q000379:methods / Q000662:veterinary*; D004624:Embryo Transfer / Q000662:veterinary; D004622:Embryo, Mammalian / Q000196:embryology; D005260:Female; D005612:Freeze Drying / Q000662:veterinary*; D008297:Male; D009865:Oocytes / Q000378:metabolism*; D011247:Pregnancy; D011256:Pregnancy Outcome / Q000662:veterinary; D051381:Rats; D017207:Rats, Sprague-Dawley; D017208:Rats, Wistar; D012662:Semen Preservation / Q000379:methods / Q000662:veterinary*; D020554:Sperm Injections, Intracytoplasmic / Q000662:veterinary