Which of the following is present in cornea?
**Core Concept**
The cornea is a complex, multi-layered tissue that forms the transparent outer layer of the eye, providing essential protection, refracting light, and facilitating vision. The cornea's unique structure and function are maintained by the presence of specific cells, proteins, and molecules.
**Why the Correct Answer is Right**
The correct answer is **B. Keratin**. The cornea's epithelial layer is composed of stratified squamous epithelial cells that contain keratin, a key structural protein essential for maintaining the integrity and transparency of the cornea. Keratin filaments provide mechanical strength, stability, and rigidity to the corneal cells, allowing them to withstand external forces and maintain the cornea's shape.
**Why Each Wrong Option is Incorrect**
**Option A:** is not present in the cornea. The cornea does not have a significant amount of muscle tissue, and the presence of muscle tissue is not a characteristic feature of this tissue.
**Option C:** is not a component of the cornea. While the cornea does contain collagen, which is a type of connective tissue protein, it is not the primary component responsible for the cornea's structure and function.
**Clinical Pearl / High-Yield Fact**
Keratin is a crucial component of the cornea's epithelial layer, and its integrity is essential for maintaining the cornea's transparency and function. Any disruption to keratin production or structure can lead to corneal disorders, such as keratoconus or corneal dystrophies.
**Correct Answer:** B. Keratin.