FIGURE 3A.

Tubulogenesis: Role of energetics in curvature formation of a tubular or cystic structure. Left panels illustrate different single mural gradients of a hormetic morphogen radiating through mural tissue with thickness δ. The hormetic morphogen gradient (top left) modulates field cell ATP generation thus forming a mural ATP gradient (middle left) that induces a mural growth gradient ΔG (bottom left) along the mural morphogen gradient. Right: The radial mural growth gradients curve the mural tissue. Tissue gradients of hormetic morphogens can thus induce concave tissue curvatures as seen from the high concentration end of morphogen gradients.