Which of the following is NOT a component of the extracellular matrix?

A. transitional epithelium - specialized for stretch: This is correctly matched. Transitional epithelium lines the urinary bladder and stretches to accommodate urine volume changes.

B. pseudostratified epithelium - multiple layers for protection: This is mismatched. Pseudostratified epithelium appears to have multiple layers due to nuclei at different levels, but all cells touch the basement membrane, so it is a single layer and not primarily for protection.

C. simple cuboidal - found in kidneys, glands, liver: Correctly matched. Simple cuboidal epithelium is commonly found in these organs and is involved in secretion and absorption.

D. keratinized stratified squamous - epidermis of skin: Correctly matched. This type of epithelium forms the outer layer of skin and provides protection against abrasion and water loss.

A. ground substance
This is a major component of the ECM, consisting of water, proteoglycans, and glycoproteins that fill the space between fibers and cells.

B. cytoplasmic inclusions
These are structures found inside the cell (e.g., glycogen granules, lipid droplets), not in the extracellular matrix.

C. fluid
Interstitial fluid (extracellular fluid) is part of the ECM and facilitates nutrient and waste exchange.

D. protein fibers
Collagen, elastic, and reticular fibers are key components of the ECM that provide strength, flexibility, and support.