Microvilli are microscopic cellular membrane protrusions that increase the surface area for absorption and secretion. These are particularly prevalent in the small intestine, where they facilitate the efficient absorption of nutrients from digested food. Each individual microvillus is typically about 0.5 to 1.0 micrometer long and 0.1 micrometer wide. They can be observed through electron microscopy, revealing their finger-like projections extending from the cell surface.
The presence of these structures significantly enhances the absorptive capacity of cells. Without them, the surface area available for nutrient uptake would be substantially reduced, hindering digestive efficiency. Their evolutionary development has been crucial for optimizing nutrient absorption in various organisms.