Human submaxillary gland. At the right is a group of mucous alveoli, at the left a group of serous alveoli.

A gland is an organ in an animal's body that synthesizes a substance for release such as hormones or breast milk, often into the bloodstream (endocrine gland) or into cavities inside the body or its outer surface (exocrine gland). Image File history File links No higher resolution available. ... Image File history File links No higher resolution available. ... Gland can refer to: a gland, an organ in an animals body that synthesizes a substance for release Gland, a commune in the Aisne département, in France Gland, a commune in the Yonne département, in France Gland, a city in Switzerland This is a disambiguation page &#8212... This article is about the biological unit. ... Hormone is also the NATO reporting name for the Soviet/Russian Kamov Ka-25 military helicopter. ... It has been suggested that the section Benefits for the infant from the article Breastfeeding be merged into this article or section. ... Human blood smear: a - erythrocytes; b - neutrophil; c - eosinophil; d - lymphocyte. ... An endocrine gland is one of a set of internal organs involved in the secretion of hormones into the blood. ... Exocrine gland refers to glands that secrete their products and temporarily store their secretions in a duct. ...

Types

Glands can be divided into two groups:

• Endocrine glands- are glands that secrete their product directly onto a surface rather than through a duct.
• Exocrine glands- secrete their products via a duct, the glands in this group can be divided into three groups:
  • Apocrine glands - a portion of the secreting cell's body is lost during secretion. Apocrine gland is often used to refer to the apocrine sweat glands, however it is thought that apocrine sweat glands may not be true apocrine glands as they may not use the apocrine method of secretion.
  • Holocrine glands - the entire cell disintegrates to secrete its substances (e.g., sebaceous glands)
  • Merocrine glands - cells secrete their substances by exocytosis (e.g., mucous and serous glands). Also called "eccrine."

The type of secretory product of an Exocrine gland may also be one of three categories: The endocrine system is a control system of ductless endocrine glands that secrete chemical messengers called hormones that circulate within the body via the bloodstream to affect distant organs. ... Exocrine gland refers to glands that secrete their products via a duct. ... Sweating (also called perspiration or sometimes transpiration) is the loss of a watery fluid, consisting mainly of sodium chloride and urea in solution, that is secreted by the sweat glands in the skin of mammals. ... Drawing of the structure of cork as it appeared under the microscope to Robert Hooke from Micrographia which is the origin of the word cell being used to describe the smallest unit of a living organism Cells in culture, stained for keratin (red) and DNA (green) The cell is the... Perspiration (also called sweating or sometimes transpiration) is the production and evaporation of a fluid, consisting primarily of water as well as a smaller amount of sodium chloride (the main constituent of table salt), that is excreted by the sweat glands in the skin of mammals. ... Holocrine is a classification of exocrine glands in the study of Histology. ... Merocrine (eccrine) is a classification of exocrine glands in the study of Histology. ... Neuron A (transmitting) to neuron B (receiving) 1. ... Exocrine gland refers to glands that secrete their products via a duct. ...

• Serous glands- secrete a watery, often protein-rich product.
• Mucous glands- secrete a viscous product, rich in carbohydrates (e.g., glycoproteins).
• Sebaceous glands- secrete a lipid product.

This page is a candidate to be moved to Wiktionary. ... The word mucous is an adjective which means pertaining to mucus or having the qualities of mucus. ... Schematic view of a hair follicle with sebaceous gland. ...

Formation

Every gland is formed by an ingrowth from an epithelial surface. This ingrowth may from the beginning possess a tubular structure, but in other instances glands may start as a solid column of cells which subsequently becomes tubulated. This article is about the epithelium as it relates to animal anatomy. ...

As growth proceeds, the column of cells may divide or give off offshoots, in which case a compound gland is formed. In many glands the number of branches is limited, in others (salivary, pancreas) a very large structure is finally formed by repeated growth and sub-division. As a rule, the branches do not unite with one another, but in one instance, the liver, this does occur when a reticulated compound gland is produced. In compound glands the more typical or secretory epithelium is found forming the terminal portion of each branch, and the uniting portions form ducts and are lined with a less modified type of epithelial cell.

Glands are classified according to their shape.

• If the gland retains its shape as a tube throughout it is termed a tubular gland.
• In the second main variety of gland the secretory portion is enlarged and the lumen variously increased in size. These are termed alveolar or saccular glands.

If a gland retains its shape as a tube throughout it is termed a tubular gland. ... Lumen can mean: Lumen (unit), the SI unit of luminous flux Lumen (anatomy), the cavity or channel within a tubular structure Thylakoid lumen, the inner membrane space of the chloroplast 141 Lumen, an asteroid discovered by the French astronomer Paul Henry in 1875 Lumen (band), an American post-rock band... In contrast to tubular glands, in the second main variety of gland, the secretory portion is enlarged and the lumen variously increased in size. ...

Specific glands

A list of human exocrine glands is available here. Exocrine gland refers to glands that secrete their products and temporarily store their secretions in a duct. ...

A list of human endocrine glands is available here. Major endocrine glands. ...

Additional images

Section of submaxillary gland of kitten. Duct semidiagrammatic. Image File history File links No higher resolution available. ... The submandibular gland (or submaxillary gland in older references) is one of the salivary glands, responsible for producing saliva. ...	Section of pancreas of dog. X 250. Image File history File links No higher resolution available. ... The pancreas is a gland organ in the digestive and endocrine systems of vertebrates. ...	Dissection of a lactating breast. Image File history File links No higher resolution available. ... For other uses, see Breast (disambiguation). ...	Section of portion of mamma. Image File history File links No higher resolution available. ... For other uses, see Breast (disambiguation). ...
Apocrine Image File history File links No higher resolution available. ...	Methods of secretion Image File history File links No higher resolution available. ...

References

• This article incorporates text from the Encyclopædia Britannica Eleventh Edition, a publication now in the public domain.