ABSTRACT
The structure of any differentiated tissue results from a well-defined sequence of events in which the spatial and temporal organization of the developing tissue mass is intimately related. More explicitly a periodic event is postulated which propagates outward from a pacemaker region, synchronizing the tissue and pro-viding a time base for development. Individual cells are supposed temporally organized in the sense that biochemical events essential for the control of development recur periodically. This temporal organization of an individual cell is converted by functional coupling between cells into a spatial ordering of the temporal organization. The chapter discusses development and regeneration in Hydra, positional in the early amphibian embryo, and the retinal-neural tectal projection of the amphibian visual system. It suggests that specific experiments to test for the existence of the postulated periodic events and their consequences.
