The generation and in vivo differentiation of murine embryonal stem cells genetically null for either N-cadherin or N- and P-cadherin.

Many mutations of the murine genome are recessive embryonic lethals precluding phenotype analysis at subsequent stages of development. This is true for embryos genetically lacking either N-cadherin or N- and P-cadherin. To circumvent this, we have generated pluripotent embryonal stem (ES) cells of the same genotype in vitro and differentiated them in vivo in the form of teratomas. All of the ES cells isolated in this study had a normal ES cell morphology in vitro and were able to generate teratomas. Histological analysis revealed that some differentiation and histogenesis had occurred within the teratomas. Epithelial formation was, for example, unaffected in all cadherin null cells. Surprisingly, however, the differentiation of cells lacking both N- and P-cadherin was, in general, even more pronounced both quantitatively and qualitatively. Tumours lacking either N- cadherin or N- and P-cadherin contained more striated muscle (apparently cardiac muscle) than heterozygote controls, and this was most strikingly conspicuous in teratomas from N- and P-cadherin null cells. This more pronounced differentiation was not seen for all tissues, however, as structures with a simple neural tube-like morphology were never found in teratomas lacking both N- and P-cadherin and organoid-like structures were rare in Ncad-/-tissue.