Glabrousness (from theLatinglaber meaning "bald", "hairless", "shaved", "smooth") is the technical term for a lack ofhair,down,setae,trichomes or other such covering. A glabrous surface may be a natural characteristic of all or part of a plant or animal, or be due to loss because of a physical condition, such asalopecia universalis in humans, which causes hair to fall out or not regrow.
Glabrousness or otherwise, of leaves, stems, and fruit is a feature commonly mentioned in plantkeys; inbotany andmycology, aglabrousmorphological feature is one that is smooth and may be glossy. It has no bristles or hair-like structures such astrichomes. In anything like the zoological sense, no plants or fungi have hair or wool, although some structures may resemble such materials.
The term "glabrous" strictly applies only to features that lacktrichomes at all times. When an organ bears trichomes at first, but loses them with age, the term used isglabrescent.
In the model plantArabidopsis thaliana, trichome formation is initiated by the GLABROUS1 protein.Knockouts of the corresponding gene lead to glabrous plants. Thisphenotype has already been used ingene editing experiments and might be of interest as a visual marker for plant research to improve gene editing methods such asCRISPR/Cas9.[1][2]
In varying degrees mostmammals have someskin areas without natural hair. Inhumans, glabrous skin is found on theventral portion of thefingers,palms,soles of feet andlips, which are all parts of the body most closely associated with interacting with the world around us,[3] as are thelabia minora andglans penis.[4] There are four main types ofmechanoreceptors in the glabrous skin of humans:Pacinian corpuscles,Meissner's corpuscles,Merkel's discs, andRuffini corpuscles.
TheNaked mole-rat (Heterocephalus glaber) has evolved skin lacking in general, pelagic hair covering, yet has retained long, very sparsely scattered tactile hairs over its body.[3] Glabrousness is a trait that may be associated withneoteny.[citation needed]
Withinentomology, the term glabrous is used to refer to those parts of an insect's body with are lacking in setae (bristles) orscales.[5]
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