magnification of the cuboidal cells (CC). Note the spherical nuclei.  These are small cells with relatively little cytoplasm, thus the nuclei appear close to one another.  The free surface of the epithelial cells face the airway (AW), whereas the basal surface of these cells rests on its basement membrane and underlying dense connective tissue (CT).
Simple cuboidal epithelium, liver, human, H&E, x450; inset x950.
This micrograph reveals cords of hepatocytes (H), simple cuboidal cells that make up the liver parenchyma. The hepatic epithelial cell cords are mostly separated from one another by blood sinusoids (S). The inset shows a higher magnification of a hepatic cell and reveals an unusual feature in that several surfaces of these cells posses a groove representing the free surface of the cell. Where the groove of one cell faces a groove of the adjacent cell, a small canal-like structure, the canaliculus (C), is formed. Bile is secreted from the cell into the canaliculus.
PLATE 1 KEY A, adipose tissue AW, airway C, canaliculus CC, cuboidal cells CT, connective tissue H, hepatocytes MC, mesothelial cells N, nucleus PCT, proximal convoluted tubule PD, pancreatic duct S, sinusoid SSE, simple squamous epithelium TB, terminal bar US, urinary space
Simple epithelia are only one cell layer thick. They are characteristic of organ systems primarily concerned with transport, absorption, and secretion, such as the intestine, the vascular system, the digestive glands and other  exocrine glands, and the kidney. Stratified epithelia have more than one layer and are typical of surfaces that are subject to frictional stress, such as skin, oral mucosa and esophagus, and vagina.
Simple epithelium, exocrine pancreas, monkey, H&E ×450.
This shows three epithelial forms. In the circle is a well-oriented acinus, a functional group of secretory cells, each of which is pyramidal in shape. The secretory cells form a spherical or tubular structure. The free surface of the cells and the lumen are located in the center of the circle. The lumen is not evident here but is evident in a similar cell arrangement in the middle right image below (see circle). Because the height of the cells (the distance from the edge of the circle to the lumen) is greater than the width, the epithelium is simple columnar. The second epithelial type is represented by a small, longitudinally sectioned duct (arrows) extending across the field. It is composed of flattened cells (note the nuclear shape), and on this basis, the epithelium is simple squamous. Finally, there is a larger cross-sectioned duct (asterisk) into which the smaller duct enters. The nuclei of this larger duct tend to be round, and the cells tend to be square in profile. Thus, these duct cells are a simple cuboidal epithelium.
Simple cuboidal epithelium, kidney, human, of a simple cuboidal epithelium. The arrows point to the lateral cell H&E ×450. boundaries; note that cell width approximates cell height. The cross-sectioned structures marked with asterisks are another type of tubule; they are
This section shows cross-sectioned tubules of several types.
smaller in diameter but are also composed of a simple cuboidal epithelium.
Those that are labeled with the  arrows provide another example
Simple columnar epithelium, colon, human, H&E ×350.
The simple columnar epithelium of the colon shown here consists of a single layer of absorptive cells and mucus-secreting cells (goblet cells). The latter can be recognized by the light
Pseudostratifed epithelium, trachea, monkey, H&E ×450.