ABSTRACT
Research applications using mouse ES cell technologies continue to expand, and are encouraging researchers to attempt to produce similar cell lines in domestic animal species. However, unlike the mouse, domestic animal ES cells with germ-line transmission capabilities remains an elusive goal. Debates continue on which in vitro environment and genetic factors are responsible for the differences observed among species. At the core of this debate is the question, should domestic animal ES be identical to mouse ES cells in respect to morphological and differentiation characteristics? Additional informative differentiation markers should help answer this question, ultimately leading to more successful ES studies in farm species. The presence and absence of molecular markers such as Oct-4, REX-1 and H-19 are well characterized in mice development. They may also be informative in farm animal embryonic development and ES cell studies. Preliminary studies using informative molecular differentiation markers will ease decisions on which putative ES cell lines to test for in vivo pluri- and totipotency. Useful in vitro data is particularly important in farm species given the huge time and resource commitments needed in well replicated in vivo potency studies. As additional cell lines are developed, research on how best to genetically engineer these cells is required to produce transgenic livestock through ES cell technology in the future.
