**Question:** The thickness of matrix band is

A. 20 nm
B. 50 nm
C. 100 nm
D. 250 nm

**Correct Answer:**

**Core Concept:** Matrix bands are lamellar units in the structure of cartilage. They consist of extracellular matrix proteins and chondrocytes embedded within them. There are three types of cartilage: hyaline, elastic, and fibrocartilage, each with its own matrix band thickness.

**Why the Correct Answer is Right:**
Matrix bands in hyaline cartilage are the thickest, measuring approximately 200 nm (nanometers). This is due to the high concentration of proteoglycans and collagen fibers within the matrix, which provides strength and elasticity to the cartilage.

**Why Each Wrong Option is Incorrect:**
A. 20 nm - This is too thin for matrix bands in hyaline cartilage, which are significantly thicker due to the dense composition.
B. 50 nm - This is roughly half the thickness of the correct answer but too thin for hyaline cartilage matrix bands.
C. 100 nm - This is also too thin for matrix bands in hyaline cartilage, which are typically around 200 nm in thickness.
D. 250 nm - This is too thick for matrix bands in hyaline cartilage, which are typically around 200 nm in thickness.

**Clinical Pearl / High-Yield Fact:**
Understanding the matrix band thickness in different types of cartilage is crucial for understanding their unique properties and biomechanical characteristics. This knowledge can be useful in assessing and interpreting clinical findings related to cartilage disorders or injuries, such as in the diagnosis of osteoarthritis or chondrodysplasia.