The Harderian gland is a gland found within the eye's
orbit
In celestial mechanics, an orbit (also known as orbital revolution) is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an ...
that occurs in
tetrapod
A tetrapod (; from Ancient Greek :wiktionary:τετρα-#Ancient Greek, τετρα- ''(tetra-)'' 'four' and :wiktionary:πούς#Ancient Greek, πούς ''(poús)'' 'foot') is any four-Limb (anatomy), limbed vertebrate animal of the clade Tetr ...
s (reptiles, amphibians, birds and mammals) that possess a
nictitating membrane.
The gland can be
compound tubular or
compound tubuloalveolar, and the fluid it secretes (
mucous,
serous or
lipid
Lipids are a broad group of organic compounds which include fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E and K), monoglycerides, diglycerides, phospholipids, and others. The functions of lipids include storing ...
) varies between different groups of animals. In some animals, it acts as an accessory to the
lacrimal gland
The lacrimal glands are paired exocrine glands, one for each eye, found in most terrestrial vertebrates and some marine mammals, that secrete the aqueous layer of the tear film. In humans, they are situated in the upper lateral region of each o ...
, secreting fluid that eases movement of the nictitating membrane. Research has proposed that the gland has several other functions, including that of a
photoprotective organ, a location of
immune response, a source of
thermoregulatory lipids, a source of
pheromone
A pheromone () is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting like hormones outside the body of the secreting individual, to affect the behavio ...
s, and a site of
osmoregulation.
[ In ]mammal
A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three ...
s, the gland secretes an oily substance used to preen the fur. The presence or absence of this gland is one of the cues used by palaeontologists to determine when fur evolved in the ancestors of mammals.anatomist
Anatomy () is the branch of morphology concerned with the study of the internal structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old scien ...
Johann Jacob Harder (1656–1711). He documented his findings in a paper titled ''Glandula nova lachrymalis una cum ductu excretorio in cervis et damis'', ("A new lachrymal gland with an excretory duct in red and fallow deer", English translation).
References
External links
Harderian Gland of Wistar Rats Revised
{Dead link, date=December 2022 , bot=InternetArchiveBot , fix-attempted=yes by Edmyr Rosa dos Reis, et al.
Vertebrate anatomy
Eye anatomy