Expression of an epidermal antigen used to study tissue induction in the early Xenopus laevis embryo.

A monoclonal antibody (Epi 1) has been produced that recognizes an antigen expressed in epidermal cells of Xenopus laevis embryos. The Epi 1 antigen appears in embryonic epidermis at the end of gastrulation and is not expressed in nonepidermal structures derived from ectoderm (for example, neural tube or cement gland). The capacity to express the Epi 1 antigen is restricted to cells of the animal hemisphere prior to the midblastula stage of development (stage 8), and tissue interactions during gastrulation inhibit the expression of the Epi 1 antigen in neural ectoderm. This epidermal antigen will be a valuable marker for studies of ectodermal commitment.