Cross section of the eye lid and the eye.
Sebaceous glands have their openings at the root of the eye lashes.
Meibomian glands are imbedded in the cartilage of the eye lid. Meibomian Glands secret oil. If the long, thin opening of the gland becomes occluded, the gland continues to secret and a small nodule is formed in the eyelid. It may become inflammed. Usually it disappeares in a few weeks.