Epithelial cornified envelope precursors are in the hair follicle and nail.

Nail and certain layers of the hair follicle form cornified envelopes (CEs) that morphologically resemble those in epidermis. We have been studying two unique precursors of the CE in human epidermis, pancornulin and sciellin. Antibodies to these proteins stained the more central cells of the outer root sheath of the ostium and isthmus of the follicle where CEs are found. Staining was also observed with these antibodies in the inner root sheath, where CEs were thought not to be present. Using immunoelectron microscopy, the staining by the sciellin antibody was at the cell periphery, but this technique did not work with the antibody to pancornulin. The antibody to pancornulin reacted to the nail fold and proximal matrix, whereas the one to sciellin reacted with the nail fold, matrix, and bed. Similar reactions were observed to monkey, sheep, and cow nail. These results suggest that envelope precursor may have an additional function in the hair follicle as well as contributing to the CE in hair and nail.