Rudimentary hemidesmosome formation in congenital generalized junctional epidermolysis bullosa in the Sprague-Dawley rat

Seven of 14 newborn pups in a litter of Sprague-Dawley rats were found to h ave generalized detachment of the epidermis, which was thin, wrinkled, and hung in loose folds over distal extremities. Histologic and ultrastructural examination of the skin showed noninflammatory separation of the epidermis from the dermis at the lamina lucida of the basement membrane zone. Ultras tructurally, hemidesmosomes were small and had a rudimentary appearance; ke ratin tonofilaments in basal keratinocytes were detached from the hemidesmo somes. The skin lesions were consistent with generalized junctional epiderm olysis bullosa, which has not previously been reported in the rat. in human s, generalized junctional epidermolysis bullosa is most commonly caused by autosomal recessive inheritance of defective proteins of the hemidesmosomes or anchoring filaments. The specific protein defect involved in the rat le sion was not determined because fresh frozen tissue was not available.