List of abbreviations
of micros-
specialist terms
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Dr. med.
H. Jastrow

of use
Overview sebaceous glands (Glandulae sebaceae):
Pages with explanations are linked to the text below the images if available! (Labelling is in German)
basal epithelial cells
epithelial cell further up 
to the lumen (monkey)
intermediate region of
a sebaceous gland 1 (rat)
intermediate region of a
sebaceous gland 2 (monkey)
degenerating cells close
to the lumen (monkey)

The majority of sebaceous holocrine glands (Terminologia histologica: Glandulae sebaceae holocrinae) are located in the areated skin of the whole body. Here they are usually associated to hair follicles delivering their secretion, i.e. sebum into the dermal papillary canal. Thus they are called hair sebaceous glands (Terminologia histologica: Glandulae sebaceae adnexa pili). An example of such a gland is the gland of Zeis (ciliary sebaceous gland; Terminologia histologica: Glandula sebacea ciliaris) a small sebaceous gland associated to the follicles of the eyelashesFurther, there are free sebaceous glands (Terminologia histologica: Glandulae sebaceae liberae) appearing with no relation to hairs. The latter are encountered on the following locations: in the outer acoustic meatus of the ear, in the outer region of the lips (where the latter in contrast to the red margins are not mechanically altered), in the area of the mamilla, on the glans of the penis, in the skin covering the labia minora and around the anus. The largest of these free glands is the gland of Meibom, a branched alveolar sebaceous gland with wide end pieces connected to a central excretory duct.
Sebaceous glands consist of differentiated epithelial cells (sebaceous gland cells; sebaceous epithelial cells; Terminologia histologica: Exocrinocyti sebacei; Epitheliocyti sebacei; Sebocyti). Their wide end pieces called alveols contain a stratified non-keratinised epitheliumPeripheral basal cells (Terminologia histologica: Cellulae basales periphericae) are located on the basement membrane of these glands and here constantly undergo mitosis whereby one daughter cell remains on place while the other is pushed into the lumen. Due to further proliferation of underlying cells it slowly reaches the excretory duct (Terminologia histologica: Ductus excretorius). Hereby the cells show more and more lipid droplets that are confluent when becoming aggregations of sebum a special composition of lipids. The nuclei as well as the organelles of the maturing cells slowly degenerate. Therefore the cells now are called vacuolated degenerating cells (Terminologia histologica: Cellulae vacuolatae degenerantes. Thus sebaceous glands secrete degraded cells proper, which comprise the sebum, through their ducts. In case of the hair associated sebaceous glands the secretion is pushed into the dermal papillary canal and slips to the surface next to the hair.
Sebaceous glands produce the sebum which makes the skin and hairs soft and shiny. It is water rejecting and inhibits proliferation of bacteria. The main components of sebum are different triglycerids and squalen. The coryne bacteria of the skin degrade the sebum to fatty acids which are partly responsible for the acid milieu on the surface of the skin. Sebaceous glands are simple of branched alveolar glands, i.e. the lumina of their glandular saccules (Terminologia histologica: Sacculi glandulares) are wide. The diameter of hair associated sebaceous glands is about 1mm.

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--> Electron microscopic atlas Overview
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Four images were kindly provided by Prof. H. Wartenberg; other image, page & copyright H. Jastrow.