Functional morphology of lesions of psoriasis vulgaris transplanted into nude mice at an early stage.

We examined the growth and differentiation of transplanted psoriatic skin in nude mice at an early stage. Psoriatic lesions from three patients were biopsied. Each biopsied specimen was cut into five blocks, which were individually transplanted to nude mice by the embedding method. Two weeks later, growth and differentiation of transplanted specimens were examined by bromodeoxyuridine (BrdU) labelling method and by electron microscopy. Electron microscopically, basal cells were longitudinally high, and the cellular processes were elongated. Basal laminae were multilayered. In the cytoplasm of the basal cells, many mitochondria, endoplasmic reticula, and ribosomes were seen, and tonofibrillar formation was poor. In cell groups in the upper parts of these lesions, both nuclei and cytoplasm showed degeneration. Psoriatic skin transplanted to nude mice exhibited newly formed psoriatic skin and initial epidermal necrosis. The BrdU labelling method labelled cells scattered in the lower part of the epidermis. Psoriatic skin transplanted to nude mice resembled that before transplantation in both ultrastructural findings and growth pattern.