title: Deep freezing of sheep embryos.
abstract: Sheep embryos, collected 1-8 days after oestrus, were placed in Dulbecco's phosphate-buffered saline medium (PBS). After treatment, the viability of the embryos was tested by temporary transfer to ligated rabbit oviducts. In Exp. 1, Days 5-8 embryos survived for at least 15 min at 0 degrees C in the presence of 1-5 M-DMSO. In Exp. 2, 12/14 Days 5-8 embryos survived after being frozen in 1-5 M-DMSO at 0-3 degrees C/min to temperatures ranging between-15 degrees and -60 degrees C and then thawed at 12 degrees C/min. In Exp. 3, Days 5-8 embryos were frozen in 1-5 M-DMSO at 0-3 degrees C/min to below-65 degrees C before being transferred to liquid nitrogen (-196 degrees C), and stored for 12 hr to 1 month. The embryos were thawed at 3 degrees C/min, 12 degrees C/MIN or 360 degrees C/min and, after transfer to rabbit oviducts, 0/4, 10/36 and 1/4, respectively, developed normally. The 11 embryos which were considered normal when recovered from the rabbit oviducts plus 1 slightly retarded embryo were transferred to 7 recipient ewes. Four ewes subsequently lambed, producing 5 lambs. In addition, 8 embryos were transferred to 4 ewes directly after thawing. Three of these ewes subsequently lambed, producing 3 lambs.
mesh_terms: D000818:Animals; D004121:Dimethyl Sulfoxide / Q000494:pharmacology; D004624:Embryo Transfer; D004622:Embryo, Mammalian / Q000166:cytology / Q000187:drug effects; D005260:Female; D005615:Freezing; D011817:Rabbits; D012756:Sheep / Q000196:embryology*; D013696:Temperature; D014021:Tissue Preservation / Q000379:methods*; D014183:Transplantation, Heterologous; D014184:Transplantation, Homologous
chemical_list: D004121:Dimethyl Sulfoxide