Developmental Pattern Formation in Phases

Cells in developing organs undergo a series of changes in their transcriptional state until a complete repertoire of cell types is specified. These changes in cell identity, together with the control of tissue growth, determine the pattern of gene expression in the tissue. Recent studies explore the dynamics of pattern formation during development and provide new insights into the control mechanisms. Changes in morphogen signalling and transcriptional networks control the specification of cell types. This is often followed by a distinct second phase, where pattern is elaborated by tissue growth. Here, we discuss the transitions between distinct phases in pattern formation. We consider the implications of the underlying mechanisms for understanding how reproducible patterns form during development.

TrendsPatterning proportions in the spinal cord change during development. This occurs in sequential phases, during which proportions are controlled by distinct mechanisms: specification in response to morphogen signalling followed by cell type-specific terminal differentiation.Mechanisms controlling tissue growth have direct and indirect effects on the establishment and dynamics of pattern.The dynamics of morphogen signalling are implicated in the transcriptional changes that accompany pattern specification and in the transitions between developmental phases.Increasing quantitative knowledge of the gene regulatory network dynamics in developmental systems extends our understanding of how pattern scaling is established.