Diagrams of a simple epithelium and the underlying mesenchyme. Outer layer of the integument is formed by an epithelial sheet epidermis derived from the ectoderm. Beneath the epithelium is a loose aggregate of mesenchyme cells derived from the mesoderm. The epithelium and the mesenchyme are separated from each other by a basal lamina. Smooth Skin forms from an epithelium called the epidermis and an underlying mesenchyme, the dermis .
Feathers form from the epidermis.
A. Presumptive feathered skin. B. A localized condensation of the mesoderm initiates formation of the dermal papilla or feather germ. C. Continued proliferation of epidermis and the underlying dermal papilla mesoderm. Separation and Recombination Experiments demonstrate that the source of the mesoderm controls the character of the specific structures formed from the ectoderm. Chicken mesoderm does not induce rachis formation from duck ectodermal epithelium.