ringed hair

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ringed hair

a rare condition in which the hair shows alternate pigmented and bright segments, the latter due to air cavities within the cortex.
Synonym(s): pili annulati
A rare autosomal dominant [MIM 180600] developmental anomaly of the hair shaft with no known clinical significance, which is characterised by alternating bands of light and dark hair due to air cavities within the shafts


1. a threadlike keratinized epidermal structure developing from a follicle sunk in the dermis, produced only by mammals and characteristic of that group of animals. Also, the aggregate of such hairs.
2. various other threadlike structures.

auditory h's
hairlike attachments of the epithelial cells of the inner ear.
awn hair
in cats, a short thick, bristly hair underneath the top coat.
hair beds
coat hairs occur in groups of about three primary follicles and a variable number of secondary follicles.
burrowing hair
one that grows horizontally in the skin.
hair cells
sensory neuroepithelial cells which have hair-like processes; found in organ of Corti, ampullary crests and utricle and saccule of the inner ear.
club hair
a hair whose root is surrounded by a bulbous enlargement composed of keratinized cells, preliminary to normal loss of the hair from the follicle.
hair coat
see coat (1).
cover hair
see guard hair (below).
hair follicle
one of the tubular invaginations of the epidermis enclosing the hair roots and from which the hairs grow.
Enlarge picture
Longitudinal section of hair follicle. By permission from Smith BP, Large Animal Internal Medicine, Mosby, 2001
hair follicle unit
hair granuloma
granuloma in the esophageal wall caused by swallowed hairs acting as foreign bodies.
hair growth cycle
a period of growth, called anagen, is followed by a transitional stage, called catagen, and then a period of inactivity in the hair follicle, called telogen, lasting until the cycle starts again. The duration of each stage varies with the species, anatomical location, genetic influence, and a variety of environmental and physiological factors.
guard hair
the coarse, stiff and often longer and more prominent hairs in a haircoat with an undercoat. For example, the darkly colored, outer hairs of a German shepherd dog. Called also primary hair, master hair, cover hair.
ingrown hair
one that has curved and re-entered the skin.
lanugo hair
the fine hair on the body of the fetus.
master hair
see guard hair (above).
primary hair
see guard hair (above).
ringed hair
see thrix annulata.
secondary hair
finer and growing from a more superficial follicle than a guard hair; forms the undercoat.
sensory h's
hairlike projections on the surface of sensory epithelial cells.
sinus hair
the vibrissae or whiskers located on the muzzle and face of many species has an endothelium-lined blood sinus between the inner and outer layers of the dermal portion of the follicle with a rich nerve supply. This structure serves to increase sensory perception.
specialized hair
includes auditory, guard, sensory, tactile, taste, tylotrich hairs (see this list).
hair streams
the hairs in the coat of animals are inclined in one or other direction so that collectively they create streams that meet at vortices or cowlicks.
tactile h's
hairs particularly sensitive to touch.
taste h's
short hairlike processes projecting freely into the lumen of the pit of a taste bud from the peripheral ends of the taste cells.
tipped hair
one with a different, usually darker, color at the tip; seen in Chinchilla cats.
tylotrich hair
special hairs that act as rapid-adapting mechanoreceptors; large, primary follicles with a ring of neurovascular tissue around them. Always associated with a tylotrich pad, a local area of epidermal thickening with a layer of highly vascular and well-innervated connective tissue below.