Expression and distribution of regeneration-responsive molecule during normal development of the newt, Cynops pyrrhogaster.

We have investigated the expression and distribution of the regeneration-responsive molecule, 2NI-36, the loss of which is responsible for initiation of dedifferentiation of dorsal marginal iris pigmented epithelial cells to regenerate a lens. In the process of the normal development of the newt, the expression of 2NI-36 could not be detected in embryos at the early developmental stages, i.e., cleavages, gastrulation and neurulation, nor through later developmental stages to tail-bud, even though organogenesis was occurring. 2NI-36 was not detectable in any tissues until embryos reached developmental stage 40 (before hatching). In hatched larvae around developmental stage 46, strong expression of 2NI-36 was observed in several tissues including the vascular endothelium, the pigmented epithelium and the inner layer of skin epidermis. Moreover, 2NI-36 was present on the cell surface of these tissue cells. In conclusion, when the embryos hatch out to become swimming larvae that can feed by themselves, 2NI-36 begins to be expressed in some kinds of differentiated tissues. These results suggest that the function of 2NI-36 might be related to the completion of morphogenesis in development and also to the stabilization of the differentiated state of newly formed tissue cells.