Fine Structure of Marsupial Hairs, with Emphasis on Trichohyalin and the Structure of the Inner Root Sheath

The study investigated the fine structure and cornification of marsupial hairs, focusing on keratins, trichohyalin, and transglutaminase using electron microscopy and immunocytochemistry. It found that the distribution of keratins in marsupial hairs is similar to that in placental mammals, primarily located in the outer root sheath and surrounding epidermis. Trichohyalin in marsupials cross-reacted with antibodies recognizing trichohyalin in placental species, indicating common epitopes. Trichohyalin granules were composed of coarse filaments within an amorphous matrix, weakly labeled for transglutaminases, suggesting an association in mature granules. Transglutaminase labeling was mainly in the condensing chromatin of mature cells, indicating nuclear envelope formation during terminal differentiation. The study also noted that the Huxley layer acts as a cushion during hair growth and that variations in its stratification relate to hair shaft diameter. The connections between cells in different layers enhance the grip of the IRS and hair fiber within the follicle, playing a role in hair shedding and exit on the epidermal surface.