The permeability of epidermis lacking normal membrane-coating granules: an ultrastructural tracer study of Kyrle-Flegel disease.

Skin lesions from patients with Flegel's disease have been reported to be without membrane-coating granules (Odland bodies). Biopsies of the hyperkeratinized papules of Kyrle-Flegel disease were incubated in vitro with the intercellular tracer, horseradish peroxidase, and the extent of penetration of this substance examined in the light and electron microscopes. The peroxidase was present throughout the corium and extended through the intercellular spaces of the epidermis to a level close to the junction of the granular and keratinized layers; it did not enter the bulk of the thickened stratum corneum of the lesion. Ultrastructural examination revealed the presence of small vesicles in the granular layer, similar in size and shape to membrane-coating granules but lacking a lamellate internal structure; these were occasionally seen fusing with the plasma membrane of the cells. It is suggested that the intercellular permeability barrier to horseradish peroxidase demonstrated in the Kyrle-Flegel lesion may arise from material contributed by these granules to the intercellular space.