Keratin Keratin Keratin () is one of a family of fibrous structural proteins. It is the key structural material making up hair, horns, claws, hooves, and the outer layer of human skin. Keratin is also the protein that protects epithelial cells from damage or stress. Keratin is extremely insoluble in water and organic solvents. Keratin monomers assemble into bundles to form intermediate filaments, which are tough and form strong unmineralized epidermal appendages found in reptiles, birds, amphibians, and mammals. The only other biological matter known to approximate the toughness of keratinized tissue is chitin. Keratin derives from Greek ' from '
Rite of Passage (The Outer Limits) extinct when the aliens found Earth, and have taken it upon themselves to restore life wherever it has vanished. Shal and Brav's child is the first human born naturally in centuries. They are given back their son and return to the commune. Rite of Passage (The Outer Limits) "Rite of Passage" is an episode of "The Outer Limits" television show. It was first broadcast on March 13, 1998, during the fourth season. The birth of a child is a joyful event, but for Shal and Brav, two young naive humans who live in a small commune in the woods, it