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RESEARCH PRODUCT

The Parasitic Colonization of the Horny Layer in Tinea Versicolor

subject

description

Observations of vertical sections and of tape strippings of areas infested with tinea versicolor indicate that because of their dimorphic state, these parasites can colonize the horny layer. Mycelial hyphae progress downwards into the intercellular spaces of the horny cells where they feed on nonkeratinous substances and extrude proliferating yeast cells which form clusters in nest-like cavities. The yeast-mycelial conversion gives rise to new mycelial hyphae and the cycle is complete. The parasites are actually lodged in tunnels and nests hollowed out in the horny layer. A dynamic balance between the cycle of the parasites and the renewal rate of the horny layer is responsible for the long duration of the lesions.