Page 133 - Atlas of Histology with Functional Correlations

The connective tissue lamina propria also contains numerous other

connective tissue cells, such as plasma cells, lymphocytes, macrophages, and
fibroblasts. These cells are normally seen with higher magnification.

FIGURE 4.6 ■ Simple columnar epithelium on villi in the small intestine: cells
with brush borders (microvilli) and goblet cells. Stain: hematoxylin and eosin.
Medium magnification.

FUNCTIONAL CORRELATIONS 4.4 ■

Epithelium with Brush Borders

(Microvilli) in Small Intestine and Kidney

The main function of the epithelium in the small intestine is absorption of
nutrients. This function is enhanced by the presence of finger-like villi,
which increase the absorptive surface area. The villi, in turn, are covered by
simple columnar epithelium with brush borders, or microvilli. These

microvilli absorb nutrients and fluids from the intestinal contents. The
intestinal epithelium also contains numerous goblet cells that secrete mucus,
which protects the intestinal epithelium from corrosive secretions that enter
the small intestine from the stomach during digestion.

Production of urine by the kidney involves filtration, absorption, and

excretion. The apical surfaces of the simple cuboidal epithelium in the
proximal convoluted tubules of the kidney are also covered with extensive
brush borders or microvilli. The main function of these microvilli is to

absorb the nutrient material and fluid from the filtrate that passes through the
tubules.

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