Question

the major regions of a hair shaft include all of the following except

cuticle

medulla

cortex

external root sheath

Explanation:

The hair shaft consists of three main regions: the cuticle (outer protective layer), the cortex (middle layer with keratin and pigment), and the medulla (central core). The external root sheath is part of the hair follicle structure, not the hair shaft.

Answer:

external root sheath