The human skin has several types of exocrine glands (Latin, glandulae cutis), which release their biochemical products onto the skin surface. All skin glands consist by a secretory compartment, the gland or coil (tubulus), and an excretory part, the duct (ductus). Skin gland cells are of epithelial origin, but their secretory compartments are located at different depths in the dermis.
Three major types of skin glands are recognized according to their product, the excretory function, and the location, where the excretory ducts release their products (diseases of these glands are listed in Table 6-1). Regarding their product, skin glands are classified into glands secreting sebum (sebaceous glands) and sweat (sweat glands). Concerning their secretory function, skin glands are classified into holocrine glands, whose fully differentiated secretory cells burst and release both the cytoplasmic content and the cell membranes into their ducts, and merocrine glands, which excrete their product via exocytosis from secretory cells. Regarding the location where their ducts release their product, the ducts of sebaceous glands, in most cases, and apocrine sweat glands excrete their products into the hair follicle canal, and the eccrine sweat glands excrete directly onto the skin surface. Sebaceous glands are holocrine glands, and sweat glands (both eccrine and apocrine ones) are merocrine glands.
Table 6-1Diseases of the Major Skin Glands ||Download (.pdf) Table 6-1 Diseases of the Major Skin Glands
Diseases of the Sebaceous Glands
Hair follicle naevus
Congenital sebaceous gland hyperplasia
Senile sebaceous gland hyperplasia
Sebaceoma (sebaceous gland epithelioma)
Senile xerosis cutis
Chlor- /dioxin-induced acne
Chemotherapy-induced diffuse alopecia
Diseases of the Eccrine Glands
Hyperhidrosis (primary and secondary)
Abnormal activity/Obstruction of the eccrine duct
Neutrophilic eccrine hidradenitis
Miliaria (crystallina, rubra, and profunda)
Diseases of the Apocrine Glands
Fox-Fordyce disease (apocrine miliaria)
Hidradenitis suppurativa (initially considered as a disease of the apocrine glands; currently as a disease of the terminal hair follicles)
Sebaceous glands are multilobular structures that consist of acini connected to a common excretory duct and are usually associated with a hair follicle.
Sebaceous glands vary considerably in size, even in the same individual and in the same anatomic area.
The sebaceous glands excrete lipids by disintegration of entire cells, a process known as holocrine secretion.
Human sebum, as it leaves the sebaceous gland, contains squalene, cholesterol, cholesterol esters, wax esters, and triglycerides.
Sebaceous glands are regulated by several molecules, among them androgens and retinoids.
ANATOMY OF THE SEBACEOUS GLANDS
Human sebaceous glands are multilobular structures of epithelial origin ...