Abstract
The establishment of new embryonic stem (ES) cell lines (A3-1, A3-2) from the blastocysts of 129/SvJ mice is described. The cells can be maintained in the undifferentiated state when grown on inactivated primary mouse embryonic fibroblast feeder layers. In suspension culture they spontaneously differentiated into embryoid bodies of increasing complexity which contained a variety of tissues including embryonic ectoderm and myocardium. The majority of the cells have kept normal set of chromosomes in Giemsa staining. Between 1 and 10 ES cells (A3-1) were introduced into the blastocoelic cavity of host-fertilized blastocysts homozygous for the dominant black locus. Eleven re-expanded blastocysts were transferred to the uterus of a recipient on the second day of pseudopregnancy, resulting in the birth of a phenotypically male chimera (agouti/albino). After mating with virgin IQI and ICR females homozygous for the albino locus, the male chimera has produced 19 agouti and 23 albino young, thus demonstrating that the transferred ES cells have c/c genotype and have colonized in the germ line.
