A cell cycle model for somitogenesis: Mathematical formulation and numerical simulation

After many years of research, the mechanisms that generate a periodic patte rn of repeated elements (somites) along the length of the embryonic body ax is is still one of the major unresolved problems in developmental biology. Here we present a mathematical formulation of the cell cycle model for somi togenesis proposed in Development 105 (1989), 119-130. Somite precursor cel ls in the node are asynchronous, and therefore, as a population, generate c ontinuously pre-somite cells which enter the segmental plate. The model mak es the hypothesis that there exists a time window within the cell cycle, ma king up one-seventh of the cycle, which gates the pre-somite cells so that they make somites discretely, seven per cycle. We show that the model can i ndeed account for the.spatiotemporal patterning of somite formation during normal development as well as the periodic abnormalities produced by heat s hock treatment. We also relate the model to recent molecular data on the pr ocess of somite formation. (C) 2000 Academic Press.