Which tissue structure is shown in the image?

• A. Blood vessel
• B. Nerve fiber
• C. Gland
• D. Cartilage

Answer: (A)

Recognize a hollow tube with a lining of endothelial cells and a layered wall around it. The image shows a round lumen with a continuous inner lining and a wall that has smooth muscle and connective tissue arranged around the circumference, which is characteristic of a blood vessel. If red blood cells are present inside the lumen, that strongly supports vascular tissue. In contrast, nerve fibers appear as parallel bundles with myelin and supporting cells, glands show secretory units and ducts, and cartilage presents chondrocytes in lacunae within a glassy, proteoglycan-rich matrix with a surrounding perichondrium. So this structure fits a blood vessel.