**Question:** Lipid in the tissues is detected by

A. Fat-soluble dyes
B. Water-soluble dyes
C. Lipid-soluble dyes
D. Specific antibodies

**Correct Answer:** C. Lipid-soluble dyes

**Core Concept:** Lipid detection in tissues is a crucial aspect of histopathological examination, particularly in diagnosing lipid storage disorders and assessing fatty infiltration.

**Why the Correct Answer is Right:**
Lipid-soluble dyes, also known as lipophilic dyes, are used for detecting lipids in tissues because they can freely diffuse through cellular membranes and accumulate within lipid droplets. These dyes are particularly suitable for staining neutral lipids, which are present in lipid storage disorders and fatty infiltration. Examples of lipid-soluble dyes include Oil Red O, Sudan series (Sudan I, II, and III), and Fontana-Masson stain.

**Why Each Wrong Option is Incorrect:**

A. Fat-soluble dyes (e.g., Oil Red FCF) are not suitable for staining neutral lipids as they are not readily taken up by the cells and do not accumulate within lipid droplets.
B. Water-soluble dyes (e.g., H&E) are primarily used for staining DNA and RNA within cells, making them unsuitable for detecting lipid storage disorders.
D. Specific antibodies target proteins and antigens, not lipids, making them irrelevant for detecting lipid storage disorders.

**Clinical Pearl:**
Understanding the appropriate stain selection is crucial for accurate diagnosis in histopathology. Different stains can highlight various components within tissues, such as lipids, proteins, or cell structures, and can provide valuable insights into pathological processes like lipid storage disorders and fatty infiltration.