Hair

Part of human hair from the the head. The image shows the
outermost layer known as the cuticle made up of several
overlapping thin layers of dead cells. The hair consists
primarily of fibrous structural proteins called keratins.

Hairs from Norwegian forest cat. Short arrow points to
attached dander from the cat. Cat dander may be
contaminated with proteins which cause allergic reactions
in sensitive humans. The long arrow points to the central
hollow core, the medulla of the hair shaft.