Identification of programmed cell death in normal human skin tissues by using specific labelling of fragmented DNA.

Programmed cell death (PCD) in normal human skin tissues was studied by using in situ specific labelling of fragmented DNA. This labelling method clearly stained the nuclei of Henle's layer in the bulb of the anagen hair follicle in serial sections, and the nuclei of the inner root sheath cuticle cells and Huxley's layer cells showed positive staining in the upper part of the hair follicles. This staining pattern was consistent with the sequence of keratinization in the three layers. The nuclei of differentiated cells located at the centre of the sebaceous glands, and those of the granular keratinocyte layer, were also stained. These findings suggest that PCD might play a key role in the terminal differentiation of the epidermis and epidermal appendages.