title: Fertilization in vitro and development to term of unfertilized mouse oocytes previously stored at --196 degrees C.
abstract: Unfertilized mouse oocytes were frozen and stored at --196 degrees C. Immediately after thawing 331 out of 463 MF1 oocytes (71-5%) and 271 out of 410 F1 (C57BL X CBA) hybrid oocytes (66-1%) were morphologically normal. No significant difference was found between the survival of oocytes frozen and thawed with (70%) or without (66%) the surrounding cumulus cells. Fertilization in vitro of frozen-thawed oocytes was significantly lower than that of freshly collected control oocytes. The overall fertilization rate in vitro for MF1 oocytes was lower than with F1 (C57BL X CBA) hybrid oocytes. The presence or absence of cumulus cells during fertilization in vitro did not affect the fertilization rate. Live 14-day fetuses were obtained after transfer of frozen-thawed unfertilized oocytes directly to the oviducts of females mated with fertile males. However, much higher rates of survival (up to 45%) to 14-day fetuses and live-born were found after the fertilization of frozen-thawed oocytes in vitro and subsequent transfer at the 2-cell or blastocyst stage to pseudopregnant recipients.
mesh_terms: D000818:Animals; D002470:Cell Survival; D004624:Embryo Transfer; D005260:Female; D005306:Fertilization / Q000187:drug effects; D005615:Freezing; D006824:Hybridization, Genetic; D066298:In Vitro Techniques; D051379:Mice; D009865:Oocytes / Q000502:physiology* / Q000637:transplantation; D010063:Ovum / Q000502:physiology*; D011247:Pregnancy; D014184:Transplantation, Homologous