Which epidermal root sheath has a single layer of tall cells next to a glassy membrane?

The correct answer is the internal epidermal root sheath. This structure is specifically characterized by a single layer of tall, columnar cells, which are positioned next to a glassy membrane known as the glassy membrane of the hair follicle. The internal epidermal root sheath plays a crucial role in the growth and formation of hair by providing support and protection to the developing hair strand as it emerges from the hair follicle.

Understanding the specific anatomy and function of the internal epidermal root sheath is fundamental in fields like dermatology and cosmetology. The relevance of this structure also extends to practices involving hair removal or alteration, as knowledge of hair follicle anatomy can influence the choice of methods for waxing or other hair treatments. Other layers and sheaths of the hair follicle serve different purposes, and while they may be important in overall hair structure, they do not share the unique characteristics of the internal epidermal root sheath.