From an electron microscopic examination of the fine structure of hairs penetrated by the dermatophyte Trichophyton mentagrophytes it was found that the penetrating organ, the invading tip of hyphae, is able to digest the several components of hair in a manner which resembles enzymatic digestion. Both components of the fibrous cortical keratin (α- and γ-) are digested as is the cell membranes of the cortical cells themselves. Hyphae penetrate between the flattened cuticle cells by digesting first the inner non-keratinous (endocuticular) component of each cell.
It is concluded that the penetrating organ may release a proteolytic enzyme whose action resembles morphologically that of trypsin on hair, and that, since even the heavily cross-linked component (γ) of the cortex is also digested, conditions leading to the rupture of disulphide bonds may also be produced.