Simple Columnar Epithelium Tissue Definition

Simple Columnar Epithelium

The cells of simple columnar epithelium are elongated; that is, they are longer than they are wide This tissue is composed of a single layer of cells whose nuclei are usually located at about the same level near the basement membrane. Simple columnar epithelium occurs in the linings of the uterus and various organs of the digestive tract, including the stomach and intestines.

Since its cells are elongated, the tissue is relatively thick, providing protection for underlying tissues. It also functions in the secretion of digestive fluids and in the absorption of nutrient molecules resulting from the digestion of foods. Columnar cells, whose principal function is absorption, often have numerous tiny, cylindrical processes extending outward from their cell surfaces.

These processes, called micro villi, are from 0.5 -1 .0 micrometer in length They function to increase the surface of the cell membrane where it is exposed to the substances being absorbed.

Typically, there arc specialized, flask-shaped glandular cells scattered along the columnar cells of this tissue. These cells, called goblet cells, secrete a thick, protective fluid called mucus onto the free surface of the tissue.