sebaceous gland


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Related to sebaceous gland: sudoriferous gland

sebaceous gland

sebaceous gland (səbāˈshəs), gland in the skin of mammals that secretes an oily substance called sebum. In humans, sebaceous glands are primarily found in association with hair follicles but also occur in hairless areas of the skin, except for the palms of the hand and soles of the feet. Sebum is a mixture of fat and the debris of dead fat-producing cells. These cells are constantly replaced by new growth at the base of the glands. Generally the sebum is deposited on the hairs inside the follicles and is brought up to the surface of the skin along the hair shaft. In hairless areas, the sebum surfaces through ducts. Sebum lubricates and protects the hair and skin and prevents drying and irritation of membranes. Sebum may collect excessively as a result of poor hygiene, a diet rich in fats, or accelerated glandular activity, especially during adolescence. Excessive secretions of sebum may be related to acne, certain forms of baldness, and other skin disorders.
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The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Sebaceous Gland

 

in humans and other mammals, a simple acinous gland with a short excretory duct and a branched end section that is located in the skin between the papillary and reticular layers of the dermis and that secretes cutaneus sebum. Sebaceous glands are distributed over the entire skin, except over the palmar and plantar surfaces.

Generally, sebaceous glands are connected to hairs: the excretory duct opens into the narrow fissure between the root and epithelial sheath of a hair. However, some glands, for example those on the lips, labia minora pudendi, nipples and nipple areas, and head and foreskin of the penis, open directly onto the body surface. The excretory duct is lined with stratified squamous epithelium, which on one side directly becomes the malpighian layer of the hair’s external root sheath and on the other becomes the wall of the alveolus. The latter consists of cells that are only slightly differentiated and capable of mitosis. These cells are rich in RNA and various enzymes and are especially concentrated near the excretory duct. The alveolus is filled with cells that contain fat droplets. Deep in the alveolus, cells undergo fatty degeneration, and as a result, their fat content increases and their nucleus wrinkles and decomposes.

Cutaneus sebum is formed from the remains of destroyed cells and fat. It serves as a fatty lubricant for the hair and skin surface and makes the skin elastic and impermeable to water, chemical substances, and certain microorganisms. The secretion of cutaneous sebum is promoted by the contraction of the skin musculature. The musk glands of certain reptiles and mammals and the uropygial glands of birds are sebaceous glands. In humans, the most common diseases of the sebaceous glands are atheroma, acne, and seborrhea.

E. S. KIRPICHNIKOVA

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

sebaceous gland

[si′bā·shəs ′gland]
(physiology)
A gland, arising in association with a hair follicle, which produces and liberates sebum.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
During the formation of the sebaceous gland, when a stem cell divided and gave rise to two daughter cells, this more often led to the formation of two new stem cells than into mature sebaceous gland cells.
Adnexal proliferations can be divided into 3 major groups on the basis of whether they show histologic differentiation resembling sebaceous glands, sweat glands/ ducts (eccrine and/or apocrine), or hair follicles.
Our findings are not consistent with other international studies where BCC was the most frequent malignant eyelid tumor, followed by SCC, sebaceous gland carcinoma and malignant melanoma.11 This could be due to geographical distribution of these malignancies, where SCC is more common in Pakistan and other Asian Countries.
MSH and ACTH, growth hormone and prolactin act directly on sebaceous glands that increases both sebum production and mitosis of sebaceous cells.
Tumor mass was histopathologically diagnosed as Sebaceous gland adenocarcinoma showing irregular multilobulated appearance of several layers of germinative sebocytes (Fig.
Key Words: White patch, ectopic sebaceous glands, Fordyces granules.
of cases incidence (%) 1 Sweat gland tumors 24 42.86 2 Sebaceous gland tumors 12 21.43 3 Hair follicle tumors 20 35.71 Total 56 100.00 TABLE 2: The site and sex distribution of observed adnexal tumors.
Hence, it has a considerable potential of mortality and morbidity.4 The prognosis of sebaceous gland carcinoma (SGC) is considered poorer than most other malignant eyelid tumours with a mortality second only to malignant melanoma (MM).5,6 Although incidence of eyelid malignancies is increasing,7-11 their global distribution is varied.
A differential diagnosis of sebaceous gland carcinoma, squamous cell carcinoma, or preseptal cellulitis was made.
If you have greasy hair, it means your sebaceous gland is overactive and you need to calm it.
Miller describes how they work: "Spot treatments work either by spreading over the dog's entire skin surface or by being absorbed through the skin at the point of application, circulating through the blood, and being transported back to the skin over the whole body through the sebaceous gland secretions.