Meibomian gland
Meibomian gland
Gray1205.png
Front of left eye with eyelids separated to show medial canthus and openings of tarsal (meibomian) glands.
Latin glandulae tarsales
Gray's subject #227 1026
MeSH Meibomian+glands

The meibomian glands (or tarsal glands) are a special kind of sebaceous gland at the rim of the eyelids inside the tarsal plate, responsible for the supply of meibum, an oily substance that prevents evaporation of the eye's tear film. They prevent tear spillage onto the cheek, trapping tears between the oiled edge and eyeball, and make the closed lids airtight.[1] There are approximately 50 glands on the upper eyelids and 25 glands on the lower eyelids. The glands are named after Heinrich Meibom (1638–1700), a German physician.

Contents

Meibum

Lipids

Lipids are the major components of meibum (also known as "meibomian gland secretions"). The term "meibum" was originally introduced by Nicolaides et al. in 1981.[2] The biochemical composition of meibum is extremely complex and very different from that of sebum. Lipids are universally recognized as major components of human and animal meibum. Recently, an update on the composition of human meibum and on the structures of various positively identified meibomian lipids was published.[3] Currently, the most sensitive and informative approach to lipidomic analysis of meibum is mass-spectrometry in combination with liquid chromatography.[4]

Proteins

In humans, more than 90 different proteins have been identified in meibomian gland secretions.[5]

Dysfunction

Dysfunctional meibomian glands often cause dry eyes, one of the more common eye conditions. They may also cause blepharitis, as the dry eyeball rubs off small pieces of skin from the eyelid, which may get infected. Inflammation of the meibomian glands (also known as meibomitis, meibomian gland dysfunction, or posterior blepharitis) causes the glands to be obstructed by thick waxy secretions. Besides leading to dry eyes, the obstructions can be degraded by bacterial lipases, resulting in the formation of free fatty acids, which irritate the eyes and sometimes cause punctate keratopathy.

References

  1. ^ "eye, human." Encyclopædia Britannica. Encyclopaedia Britannica Ultimate Reference Suite. Chicago: Encyclopædia Britannica, 2010.
  2. ^ Nicolaides N, Kaitaranta JK, Rawdah TN, Macy JI, Boswell FM 3rd, Smith RE. "Meibomian gland studies: comparison of steer and human lipids." Invest Ophthalmol Vis Sci. 1981 Apr;20(4):522-536. PMID 7194326.
  3. ^ Butovich IA (November 2009). "The Meibomian puzzle: combining pieces together". Prog Retin Eye Res 28 (6): 483–498. doi:10.1016/j.preteyeres.2009.07.002. PMID 19660571. 
  4. ^ Butovich IA. "Lipidomic analysis of human meibum using HPLC-MSn." Methods Mol Biol. 2009;579:221-246. PMID 19763478.
  5. ^ Tsai PS, Evans JE, Green KM, Sullivan RM, Schaumberg DA, Richards SM, Dana MR, Sullivan DA. "Proteomic analysis of human meibomian gland secretions." Br J Ophthalmol. 2006 March;90(3):372-7. doi:10.1136/bjo.2005.080846 PMID 16488965.

External links


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Look at other dictionaries:

  • Meibomian gland — noun a long sebaceous gland that lubricates the eyelids bacterial infection of a Meibomian gland produces a stye • Syn: ↑tarsal gland • Hypernyms: ↑sebaceous gland, ↑sebaceous follicle, ↑glandulae sebaceae * * * (ˈ)mī|bōmēən, myən …   Useful english dictionary

  • meibomian gland — mei·bo·mian gland mī bō mē ən n, often cap M one of the long sebaceous glands of the eyelids that discharge a fatty secretion which lubricates the eyelids called also tarsal gland see CHALAZION Mei·bom mī .bōm Heinrich (1638 1700) German… …   Medical dictionary

  • Gland of Moll — Glands of Moll, also known as ciliary glands, are modified apocrine sweat glands that are found on the margin of the eyelid. They are next to the base of the eyelashes, and anterior to the Meibomian glands within the distal eyelid margin. These… …   Wikipedia

  • meibomian stye — a stye involving a meibomian gland, usually draining through the conjunctival surface of the lid …   Medical dictionary

  • Meibomian cyst — noun a small sebaceous cyst of the eyelid resulting when a Meibomian gland is blocked • Syn: ↑chalazion • Hypernyms: ↑sebaceous cyst, ↑pilar cyst, ↑wen, ↑steatocystoma …   Useful english dictionary

  • gland — An organized aggregation of cells functioning as a secretory or excretory organ. SYN: glandula (1) [TA]. [L. glans, acorn] accessory g. a small mass of glandular structure, detached from but lying near another and larger g., to which it is… …   Medical dictionary

  • tarsal gland — noun a long sebaceous gland that lubricates the eyelids bacterial infection of a Meibomian gland produces a stye • Syn: ↑Meibomian gland • Hypernyms: ↑sebaceous gland, ↑sebaceous follicle, ↑glandulae sebaceae * * * noun …   Useful english dictionary

  • Sebaceous gland — Infobox Anatomy Name = Sebaceous gland Latin = glandula sebacea GraySubject = 234 GrayPage = 1069 Caption = Schematic view of a hair follicle with sebaceous gland. Caption2 = Cross section of all skin layers. A hair follicle with associated… …   Wikipedia

  • sebaceous gland — noun a cutaneous gland that secretes sebum (usually into a hair follicle) for lubricating hair and skin • Syn: ↑sebaceous follicle, ↑glandulae sebaceae • Hypernyms: ↑oil gland • Hyponyms: ↑Meibomian gland, ↑tarsal gland, ↑ …   Useful english dictionary

  • tarsal gland — n MEIBOMIAN GLAND …   Medical dictionary

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