Related topics: stem cells

Here today, gone tomorrow: How humans lost their body hair

Orangutans, mice, and horses are covered with it, but humans aren't. Why we have significantly less body hair than most other mammals has long remained a mystery. But a first-of-its-kind comparison of genetic codes from 62 ...

A checkerboard pattern of inner ear cells enables us to hear

A Japanese research group has become the first to reveal that the checkerboard-like arrangement of cells in the inner ear's organ of Corti is vital for hearing. The discovery gives new insight into how hearing works from ...

When was the first time life began to prey on each other?

Using the word predation may seem surprising when we talk about the first organisms that set out to eat other organisms, for they were not deadly predators with sharp teeth and claws, but small single-celled life forms that ...

Why aren't all black bears black?

Sometimes a name is just a name. Take bears, for example. In Yellowstone National Park, black bears outnumber their brownish-colored grizzly bear cousins, and in coastal areas of the Pacific Northwest, if someone says "brown ...

High-resolution microscopy for analysis of protein complexes

Researchers at Forschungszentrum Jülich and the Berlin Institute of Health at Berlin's Charité Hospital have developed a novel method for determining the number of subunits within protein complexes. The method is a further ...

Physical theory describes movements of micro-hairs

They are only very simple structures, but without them we could not survive: Countless tiny hairs (cilia) are found on the outer wall of some cells, for example in our lungs or in our brain. When these micrometer-sized hairs ...

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Hair

Hair is a protein filament that grows through the epidermis from follicles deep within the dermis. The fine, soft hair found on many nonhuman mammals is typically called fur; wool is the characteristically curly hair found on sheep and goats. Found exclusively in mammals, hair is one of the defining characteristics of the mammalian class. Although other non-mammals, especially insects, show filamentous outgrowths, these are not considered "hair" in the scientific sense. So-called "hairs" (trichomes) are also found on plants. The projections on arthropods such as insects and spiders are actually insect bristles, composed of a polysaccharide called chitin. There are varieties of cats, dogs, and mice bred to have little or no visible fur. In some species, hair is absent at certain stages of life. The main component of hair fiber is keratin.

The hair can be divided into three parts length-wise, (1) the bulb, a swelling at the base which originates from the dermis, (2) the root, which is the hair lying beneath the skin surface, and (3) the shaft, which is the hair above the skin surface. In cross-section, there are also three parts, (1) the medulla, an area in the core which contains loose cells and airspaces (2) the cortex, which contains densely packed keratin and (3) the cuticle, which is a single layer of cells arranged like roof shingles.

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