Abstract
Electron microscopic investigation was made on the guinea pigs epidermis after topical application of 1α,25-dihydroxyvitamin D3 5 μg ointment for four weeks. Histologically, the epidermis exhibited a thickening of the granular layer with mild acanthosis. Electron microscopically, the nuclei of the basal cells were large and the nuclear membrane was irregular. In the cytoplasm, numerous vacuoles and tonofibrillar formation were present and the intercellular spaces were widened. In the spinous cell layer, findings of nuclei and cytoplasm were similar to the events seen in the controls. In the thickened granular layer, small-sized and irregular-shaped keratohyalin granules were present in the lower part, and large-sized keratohyalin granules were seen in the upper part. The horny layer had a keratin pattern. Therefore, we consider that topical application of 1α,25-dihydroxyvitamin D3 influences differentiation or keratinization processes of the epidermal keratinocytes.
