Eccrine sweat glands

Eccrine sweat gland
A sectional view of the skin (magnified), with eccrine glands highlighted.
Details
Precursor	Ectoderm
System	Integumentary
Nerve	Cholinergic sympathetic nerves
Identifiers
Latin	Glandula sudorifera merocrina; Glandula sudorifera eccrina
MeSH	A10.336.899.480
TH	H3.12.00.3.03009
FMA	59154
Anatomical terminology []

Eccrine glands (/ˈɛkrən/, /ˈɛˌkraɪn/, or /ˈɛˌkrin/; from ekkrinein "secrete"; sometimes called merocrine glands) are the major sweat glands of the human body, found in virtually all skin, with the highest density in palms and soles, then on the head, but much less on the trunk and the extremities. In lower mammals, they are relatively sparse, being found mainly on hairless areas such as foot pads. They reach their peak of development in humans, where they may number 200–400/cm² of skin surface. They produce a clear, odorless substance, consisting primarily of water.

Eccrine glands are composed of an intraepidermal spiral duct, the "acrosyringium"; a dermal duct, consisting of a straight and coiled portion; and a secretory tubule, coiled deep in the dermis or hypodermis. The eccrine gland opens out through the sweat pore. The coiled portion is formed by two concentric layer of columnar or cuboidal epithelial cells. The epithelial cells are interposed by the myoepithelial cells. Myoepithelial cells support the secretory epithelial cells. The duct of eccrine gland is formed by two layers of cuboidal epithelial cells.

Eccrine glands are active in thermoregulation by providing cooling from water evaporation of sweat secreted by the glands on the body surface and emotional induced sweating (anxiety, fear, stress, and pain). The white sediment in otherwise colorless eccrine secretions is caused by evaporation that increases the concentration of salts.