Cloning the laboratory mouse.
A brief account is given of early attempts to clone mammals (mice) by transferring cells (nuclei) of preimplantation embryos into enucleated oocytes, zygotes or blastomeres of two-cell embryos. This is followed by a brief review of recent successes using adult somatic cells: mammary gland cells for sheep, muscle cells for cattle and cumulus cells for mice. We have developed a technique for cloning the laboratory mouse by transferring cumulus cell nuclei into enucleated oocytes. With this technique, we have produced a population of over 80 cloned animals, and have carried the process over four generations. Development and fertility of these appear normal. However, the yield is very low; only approximately 1% of injected oocytes are carried to term. The challenge is now to understand the reason for this high loss. Is it a problem of technique, genomic reprogramming, somatic mutation, imprinting or incompatible cell cycle phases?
Wakayama
T
T
Department of Anatomy and Reproductive Biology, University of Hawaii Medical School, Honolulu, Hawaii 96822, USA.
Yanagimachi
R
R
D000818:Animals; D002453:Cell Cycle / Q000235:genetics; D002467:Cell Nucleus / Q000235:genetics; D002678:Chimera / Q000235:genetics; D019976:Cloning, Organism / Q000379:methods*; D010064:Embryo Implantation / Q000235:genetics; D004622:Embryo, Mammalian / Q000166:cytology; D005314:Embryonic and Fetal Development; D005260:Female; D005333:Fetus / Q000166:cytology; D006822:Hybrid Cells / Q000166:cytology; D008297:Male; D051379:Mice; D008822:Mice, Transgenic / Q000235:genetics*; D053652:Nuclear Transfer Techniques; D009865:Oocytes / Q000166:cytology