Patterns of Organogenesis Studied by Cell Labelling in Mouse Chimeras

Developmental biology of multi-cellular animals comprises the progressive transformation of the fertilized egg into an adult of approximately a trillion cells in case of the mouse. During this process, organs and tissues derive from individual progenitor pools, and in each of these a characteristic cocktail of morphogenetic mechanisms, like proliferation of cell clones, cell migration and mixing, and programmed cell death (apoptosis) leads to characteristic spatial patterns in the mature organs. Some of these events can be examined retrospectively by genetic cell labelling techniques in artificial chimaeras; e.g. by marking a fraction of cells in an early embryonic stage followed by retrospective analysis of the derived mosaic; these techniques have been applied to the mouse for many years (cf. [1]). We have used green fluorescent transgenic mice [2] to label cells for parental origin in combination with unlabelled mice to produce mouse chimeras [3]. Tissues of these contain green fluorescent labelled cell patches, which morphology and distribution are historical records of underlying developmental processes and enable to develop models of organ development. Examples for the clonal cell distribution patterns in the heart, skeletal [3] and smooth muscle tissue, and the pancreas will be presented.

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2. Jockusch, H., Voigt, S., Eberhard, D. (2003), J Histochem Cytochem, 3, 401- 4.
3. Eberhard, D. and Jockusch, H. (2004) Developmental Dynamics. In press.