Figure 2.
Cellular condensations depicted as an aggregation event, around a central locus for the case of a bulbous mesenchymal core (A), and as a core expanding about a center of mitotic activity (B). In the former case, the ectoderm or bounding sheath counteracts the compression of the mesoderm. In the latter case, the ectoderm resists the forces of expansion. Of note, each point in space within the condensing mesenchyme is subjected to a unique combination of stresses and mechanically modulated chemical gradients due to imperfect symmetry in boundary conditions and inhomogeneities in the mesenchyme.