**Question:** Ocular basement membrane is stained by

A. DAPI
B. Masson's Trichrome
C. Picrosirius red
D. H&E stain

**Correct Answer:** C. Picrosirius red

**Core Concept:** Ocular basement membrane is a thin, dense, fibrous layer that forms the structural support for various ocular tissues, including the cornea, lens, and conjunctiva. Different stains are used for various tissues and structures to highlight their unique characteristics.

**Why the Correct Answer is Right:** Picrosirius red is a specific stain used to visualize collagen fibers due to its interaction with collagen molecules. In this case, Picrosirius red stain highlights the collagen fibers of the ocular basement membrane, making it visible and distinct from surrounding tissues during histopathological examination.

**Why Each Wrong Option is Incorrect:**

A. DAPI (4',6-diamidino-2-phenylindole) is a fluorescent dye used for nuclear staining, specifically targeting the DNA or RNA of cells. It is not used for staining basement membranes.

B. Masson's Trichrome stain is a general stains that includes a blue (collagen) and red (myofibroblasts) component. While it can stain collagen fibers, it does not specifically target basement membranes.

D. H&E stain (Hematoxylin and Eosin) is a general staining technique used for histology, primarily staining nuclei and cytoplasm, respectively. It does not specifically stain basement membranes.

**Clinical Pearl:** Understanding the appropriate staining techniques is essential for accurate histopathological diagnosis, as it enables pathologists to visualize and differentiate various tissues, cells, and structures. Knowledge of staining methods is crucial for interpreting the histopathological findings accurately and drawing appropriate conclusions regarding the specimen being examined.