Regulation of gastrulation movements by emergent cell and tissue interactions

Abstract

It is during gastrulation that the primordial germ layers are specified, embryonic axes become morphologically manifest, and the embryonic body plan begins to take shape. As morphogenetic movements push and pull nascent tissues into position within the gastrula, new interactions are established between neighboring cells and tissues. These interactions represent an emergent property within gastrulating embryos, and serve to regulate and promote ensuing morphogenesis that establishes the next set of cell/tissue contacts, and so on. Several recent studies demonstrate the critical roles of such interactions during gastrulation, including those between germ layers, along embryonic axes, and at tissue boundaries. Emergent tissue interactions result from - and result in - morphogen signaling, cell contacts, and mechanical forces within the gastrula. Together, these comprise a dynamic and complex regulatory cascade that drives gastrulation morphogenesis.

Figure 1. Emergent cell and tissue interactions during gastrulation

Examples of cell and tissue interactions in Xenopus (A–A”), Zebrafish (B,B’), and Drosophila (C–C”) gastrulae. A) A’ depicts vertical interactions that establish a boundary between nascent mesoderm (red) and ectoderm (blue). A” depicts accumulation of Myosin at the boundary between axial (purple) and paraxial (red) mesoderm and at AP cell junctions. Dorsal is to the right. B) B’ depicts migration of endoderm cells (yellow) along the mesoderm layer (red). Gray triangles represent Wnt and BMP signaling gradients with important roles in gastrula patterning and morphogenesis. Dorsal is to the right. C) C’ depicts Myosin accumulation at boundaries between AP body parasegments (shown in pink, purple, and green). Anterior is to the left.