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"For most tissues in the body it is not known whether growth and replenishment is achieved by adult stem cells or by the proliferation of pre-existing differentiated cells. This is particularly important in the case of pancreatic beta cells, which are destroyed in type I diabetes. A transgenic mouse system for tracing the origins of adult beta cells was constructed by expressing tamoxifen-dependent cre recombinase, combined with a cre reporter gene, in pancreatic beta cells. In such transgenic mice existing beta cells can be genetically labeled, so that new beta cells forming by stem cell differentiation can be distinguished from new beta cells generated by the duplication of pre-existing beta cells. The image shows one islet from such a mouse, stained for insulin (pink), the alkaline phosphatase cre reporter gene (blue) and DNA (green)." |
