villi
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Tiny finger-like projections lining the small intestine — the gut's primary nutrient-absorbing surface.
Villi (singular: villus) are microscopic projections, roughly 0.5–1.6mm tall, covering the inner wall of the small intestine like dense carpet fibres. Each villus is itself covered in even tinier projections called microvilli (the "brush border"), multiplying the surface area further. Together, villi increase the gut's absorptive surface area to roughly the size of a tennis court — allowing efficient extraction of nutrients from food as it passes through.
Structure
Each villus contains:
- A core of connective tissue and blood vessels (capillaries and lymphatics)
- A surface layer of enterocytes — absorptive cells that do the actual work of transporting nutrients into the bloodstream
- Interspersed intraepithelial-lymphocytes (IELs) — immune sentinel cells
At the base of each villus, the crypts of Lieberkühn continuously produce new enterocytes to replace those shed from the villus tips (normal turnover is ~2–5 days).
In Celiac Disease
The immune attack on the intestinal lining progressively damages and destroys villi — a process called villous-atrophy. As villi flatten, absorptive surface area plummets. The loss drives malabsorption of virtually all nutrients, since the entire proximal small intestine (duodenum and jejunum) is the primary absorption zone and is hardest hit.
On a gluten-free-diet, villi gradually regenerate. Full recovery can take months to years and is a key monitoring target in management.
Related Concepts
villous-atrophy | malabsorption | enterocytes | intraepithelial-lymphocytes | crypt-hyperplasia | small-intestine
Referenced In
mechanism | diagnosis | symptoms | management