Skin

This cross section of a hair shaft is useful to delineate the various layers. The most interior cells form the medulla, then cortex, and finally a layer of flatter cells, the cuticle. The internal root sheath is composed of three layers, and is covered by the external root sheath. The basal lamina is thickened to form the glassy membrane. The whole structure is then encased in a connective tissue sheath. Identify the sweat duct. UCLA Histology Collection.