CRYOPRESERVATION OF WILD MOUSE SPERMATOZOA

Spermatozoa of wild mice from China, Czechoslovakia, Denmark, India, J apan and Switzerland were frozen and stored at -196 degrees C. After t hawing, intact oocytes were inseminated in vitro with relatively high motility frozen-thawed mouse spermatozoa from Czechoslovekia, Denmark and India, while oocytes with a partially dissected zona were insemina ted with low motility frozen-thawed spermatozoa from China, Japan and Switzerland. Embryos developing to the 2-cell stage from oocytes ferti lized with frozen-thawed spermatozoa were transferred to the oviducts of female recipients on the first day of pseudopregnancy (day when a v aginal plug was confirmed). Successful embryo development to the 2-cel l stage was 46 to 67%. Offspring resulted from 17 to 51% of these tran sferred 2-cell embryos.