What Are Microvilli?

Microvillus, also known as fine villi and villous processes, are widely found on the surface of animal cells. It can be observed under an electron microscope that microvilli are fine finger-like protrusions protruding from the cell membrane and cytoplasm of the free surface of the cell, surrounded by the cell membrane and perpendicular to the surface of the cell membrane. It varies widely and exists widely in animal cells. However, the cells with strong absorption functions, such as oocytes, small intestines, and tubules of the urinary tubules in the growing stage, and the inner ear, nose, and lateral lines More abundant in cells. The surface of the microvilli is a cytoplasmic membrane and a sugar coat, and the interior is an extension of the cytoplasm. In the longitudinal section, there are many longitudinally arranged microfilaments in the center of the microvilli, reaching the top of the microvilli, and the diameter of the microfilaments is 4-6 nm. Below the cytoplasmic membrane of epithelial cells, there is a micro-mesh that is parallel to the cytoplasmic membrane called the terminal web. The roots of the microfilaments in the microvilli are buried in the terminal web. These structures all enhance the firmness of the top of the cell, making the surface of the epithelium a whole.

Microvilli

In addition, when the sea urchin egg cells are fertilized, there are many villi on the cell surface, especially on the surface of the epithelial cells of the small intestine and renal tubules. . Under high-power microscopy, the free surface of the cell shows a longitudinal striated border or brush border. One small cell of the small intestine has about 3,000 microvilli, which can be regarded as a device that increases the free surface of cells and improves the ability to absorb and receive stimulation.

It is located on the free surface of epithelial cells. Electron microscopy is used to observe the finger-shaped protrusions formed by the cell membrane and cytoplasm.

Microvilli are not visible under an optical microscope, but only under a microscope such as an electron microscope.