Description
Haploid stem cells offer an easy-to-manipulate genetic system and therefore have great values for studies of recessive phenotypes. Here, we show that mouse androgenetic haploid ES (ahES) cell lines can be established by transferring sperm into enucleated oocyte. The ahES cells maintain haploidy and stable growth over 30 passages, express pluripotent markers, possess the ability to differentiate into all three germ-layers in vitro and in vivo, and contribute to germline of chimeras when injected into blastocysts. Although epigenetically distinct from sperm cells, the ahES cells can produce viable and fertile progenies after intracytoplasmic injection into mature oocytes. The oocyte injection procedure can also produce viable transgenic mice from genetically engineered ahES cells.