Cartilage receives nutrients primarily through diffusion from surrounding tissues because it lacks its own blood supply.
Here's a more detailed explanation:
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Avascular Nature: Cartilage is an avascular tissue, meaning it does not contain blood vessels. This absence of direct blood supply necessitates alternative methods for nutrient delivery.
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Perichondrium: Most cartilage types are surrounded by a dense connective tissue layer called the perichondrium. The perichondrium is vascularized, containing blood vessels that supply oxygen and nutrients.
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Diffusion: Nutrients and oxygen from the blood vessels within the perichondrium must diffuse through the extracellular matrix of the cartilage to reach the chondrocytes (cartilage cells). This diffusion process is relatively slow.
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Synovial Fluid (in Articular Cartilage): Articular cartilage, found in joints, lacks a perichondrium. It receives nutrients primarily from the synovial fluid present in the joint cavity. The synovial fluid is nourished by capillaries in the surrounding synovial membrane. Movement and weight-bearing help to distribute nutrients from the synovial fluid into the cartilage.
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Subchondral Bone: A small amount of nutrient exchange may occur with the subchondral bone that lies beneath the articular cartilage.
In summary, cartilage relies on diffusion from the perichondrium (if present) or synovial fluid to obtain the necessary nutrients for cell survival and tissue maintenance due to its avascular nature.
