There is a significant, bilateral pattern, and differences are most pronounced in axial levels that are folding and rotating. Folding endoderm to form gut tube appears to be a process that is driven by domains of high cell proliferation flanking a domain of significantly lower proliferation. When considered in the context of an epithelium attached to subjacent mesoderm, these differentials could produce a forced and directed buckling of endoderm into lateral folds that join and enclose a tube.
Patterns suggest that endoderm folds about a median hinge.
Hamilton College Academic Fund for Seniors. The proliferative hinge in median endoderm . Data taken from comparable sites and axial levels within the same chick embryos show different profiles of proliferation during folding of these membranes. An enlarged tracing of a representative section shows placement of sample sites and helps to place the statistics into morphological perspective. Gray in the data graphs indicates areas between body folds in each layer as clarified by arrrows from the tracing.