Glands of Moll, also known as ciliary glands, are modified apocrine

Apocrine

Apocrine is a term used to classify exocrine glands in the study of histology. Cells which are classified as apocrine bud their secretions off through the plasma membrane producing membrane-bound vesicles in the lumen. This method is also called decapitation secretion...

 sweat glands that are found on the margin of the eyelid

Eyelid

An eyelid is a thin fold of skin that covers and protects an eye. With the exception of the prepuce and the labia minora, it has the thinnest skin of the whole body. The levator palpebrae superioris muscle retracts the eyelid to "open" the eye. This can be either voluntarily or involuntarily...

. They are next to the base of the eyelash

Eyelash

An eyelash or simply lash is one of the hairs that grow at the edge of the eyelid. Eyelashes protect the eye from debris and perform some of the same function as whiskers do on a cat or a mouse in the sense that they are sensitive to being touched, thus providing a warning that an object is near...

es, and anterior to the Meibomian glands within the distal eyelid margin. These glands are relatively large and tubular-shaped.

Moll's glands empty into the adjacent lashes. Glands of Moll and Zeis

Glands of Zeis

Glands of Zeis are unilobar sebaceous glands located on the margin of the eyelid. The glands of Zeis service the eyelash. These glands produce an oily substance that is issued through the excretory ducts of the sebaceous lobule into the middle portion of the hair follicle...

 secrete lipid that adds to the superficial layer of the tear film

Tears

Tears are secretions that clean and lubricate the eyes. Lacrimation or lachrymation is the production or shedding of tears....

, retarding evaporation.

The glands of Moll are prone to infection and blockage of its duct with sebum and cell debris. Blockage of the gland's duct causes swelling which can manifest itself as a stye

Stye

An external stye or sty , also hordeolum , is an infection of the sebaceous glands of Zeis at the base of the eyelashes, or an infection of the apocrine sweat glands of Moll. External styes form on the outside of the lids and can be seen as small red bumps. Internal styes are infections of the...

. The glands of Moll are named after Dutch oculist Jacob Anton Moll (1832–1914).