Final answer:
The cortex in hair is the middle layer of the hair shaft, which includes keratinocytes responsible for keratin production, pigment granules for hair color, and cortical cells that form the majority of the hair shaft.
Step-by-step explanation:
The cortex in hair is the second or middle layer of the hair shaft, comprised primarily of keratinocytes which originate from the hair matrix. Three structures found within the cortex include:
- Keratinocytes: These are the cells that produce keratin, a type of protein that strengthens hair and gives it structure.
- Pigment granules: These granules are responsible for giving the hair its color.
- Cortical cells: These are elongated cells that form the bulk of the hair shaft and are rich in keratin.
Additionally, the hair cuticle covers the cortex, providing an outer layer of protection, while the medulla forms the innermost core of specially structured cells.
Hair texture, such as straight or curly, is largely determined by the shape and structure of the cortex and, to some extent, the medulla. The hair follicle's shape also plays a crucial role in determining these characteristics.