Ultrastructural studies of barrier restoration in epidermis of hairless mice following dimethyl sulfoxide application.

Sixteen hairless mice were studied by transmission electron microscopy to determine the ultrastructural changes in epidermal barrier restoration following topical applications of dimethyl sulfoxide (DMSO) to back skin. Samples of experimental skin were examined at 30 min, 1 h, 2 h and 3 h after the initial DMSO treatment and compared with that of control animals. At earlier time periods (30 min-1 h) the DMSO treated epidermis showed greatly expanded intercellular spaces, disrupted desmosomal attachments, and desmosomal remnants lying free within the intercellular space. Mitochondria contained droplets of lipoid material which reached maximum size in the spinous and granular layers. Cytoplasmic vacuoles were particularly prominent in the 30-min samples. Large numbers of membrane coating granules (MCG) emerged in the 1 h specimens. The MCG were laden with numerous electron-dense inner membranes which crisscrossed at various angles. Many of the MCG were observed in the process of fusion with plasma membranes of granular cells adjacent to the stratum corneum. At 2 h a process of recovery from the effects of DMSO was evident and at 3 h there was little or no difference between experimental and control epidermis.