Glands of Zeis are:
**Core Concept**
The glands of Zeis are small sebaceous glands located at the margin of the eyelids, associated with the eyelashes. They are a type of apocrine gland that plays a role in the production of sebum, contributing to the lubrication and protection of the eyelashes.
**Why the Correct Answer is Right**
The glands of Zeis are responsible for producing sebum, which is secreted onto the eyelashes to help maintain their health and prevent dryness. This sebum also helps to protect the eyelashes from damage and promotes their growth. The glands are innervated by the sympathetic nervous system, which regulates their secretory activity.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the meibomian glands are a different type of sebaceous gland located within the tarsal plates of the eyelids, not at the margin.
**Option B:** This option is incorrect because the ciliary glands are small mucus-producing glands located near the lacrimal canaliculi, not associated with the eyelashes.
**Option C:** This option is incorrect because the lacrimal glands are the primary source of tears, not associated with the production of sebum.
**Clinical Pearl / High-Yield Fact**
The glands of Zeis are an important component of the eyelid anatomy, and their dysfunction can contribute to conditions such as blepharitis, a common inflammatory disorder of the eyelids.
**Correct Answer: C. Meibomian glands are located within the tarsal plates of the eyelids, whereas the glands of Zeis are located at the margin of the eyelids and are associated with the eyelashes.