A novel antigen is shared by retinal pigment epithelium and pigmented neural crest

Pigment cells in vertebrate embryos are formed in both the central and peripheral nervous system. The neural crest, a largely pluripotent population of precursor cells derived from the embryonic neural tube, gives rise to pigment cells which migrate widely in head and trunk.The retinal pigment epithelium is derived from the optic cup, which arises from ectoderm of the neural tube. We have generated an antibody, ips6, which stains an antigen common to pigment cells of retinal pigment epithelium and neural crest. Ips6 stains retinal pigment epithelium and choroid as well as a subset of crest cells that migrate in pathways typical of melanoblasts. Immunoreactivity is seen first in the eye and later in a subset of migrating crest cells. Crest cells in the amphibian embryo migrate along specific, stereotyped routes; ips6 immunoreactive cells are found in some but not all of these pathways. In older wild-type embryos, cells expressing ips6 appear coincident with pigment-containing cells in the flank, head, eye and embryonic gut. In older animals, staining in the eye extends to the intraretinal segment of optic nerve and interstices between photoreceptors and cells at the retinal periphery. We suggest that the ips6 antibody defines an antigen common to pigment cells of central and peripheral origin.