Ultrastructure of the lesions of psoriasis vulgaris transplanted into the subcutaneous tissue of nude mice by the skin fenestrating transplantation method.

We have developed a new skin transplantation method, called the skin fenestrating transplantation method, in which the nude mouse skin covering the lesion was removed one week after the transplant was embedded. One week later, transplanted psoriatic skin was biopsied and specimens were examined by electron microscopy. The basal cells and the nuclei of transplanted psoriatic epidermis were long and slender. Projections of basal cells extended to the dermis. Erythrocytes and lymphocytes were seen in the intercellular space. In the spinous cell layer, the cytoplasm and the nuclei were round. In the cytoplasm, mitochondria and endoplasmic reticuli were abundant, and tonofibrillar formation was poor. In the upper part of the epidermis, the cells were horizontally elliptic and, in the cytoplasm, short tonofibril bundles were formed. In the uppermost layers, in the cytoplasm of flat cells, degenerated flat nuclei, low dense lipid droplets and clumps of ribosomes were observed. These findings resembled the findings of intact psoriasis lesions more closely than those obtained by the skin embedding transplantation method.