ON A TISSUE INTERACTION-MODEL FOR SKIN PATTERN-FORMATION

There is now sound biological evidence that dermal-epidermal communication is essential in the formation of skin organs. Recent experimental results suggest that cell adhesion molecules (CAMs) play an important role during skin pattern formation. We describe here a tissue interaction model for pattern morphogenesis in vertebrate skin which includes such CAMs. A mechanochemical mechanism is used to describe epithelial sheet motion, and a reaction-diffusion-chemotaxis mechanism is used to model the dermal cell movements. Neither of the mechanisms can independently generate spatial patterns in their respective layers. Tissue interaction is introduced using morphogens produced separately in the dermis and epithelium. These morphogens diffuse across the basal lamina, which separates the epidermis and dermis, and induce cell movements and deformation. Analysis of a simplified one-dimensional version shows that under certain conditions spatial patterns can be formed. A nonlinear analysis predicts the solution behavior which is in close agreement with the numerical results.