Fine structure of the fully keratinized hair cuticle in the head hair of the human.
The cuticle is composed of five cell layers in the cross section of the hair at a level of 100 mm above the scalp. Intercellular junctions between two cuticular cells are zonulae occludentes (tight junction); they consist of five layers. The gap junctions of the intercellular communications occur near the cortex. The trichohyalin granule appears in the cuticular cells of completely cornified head hair. The granule is generally smaller than that of the keratohyalin granule, and spherical in shape. The granule is not visible in the area near the surface of the hair. The keratin in the cytoplasm of the cuticular cell may originate from the trichohyalin granule.
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