The basal layer, located at the deepest part of the epithelium, rests on the underlying connective tissue. The nuclei of the epithelial cells are very close to one another, indicating that the cells have relatively little cytoplasm.
A little farther from the basal layer, the cells become larger, and their nuclei are more widely separated. At this level, the cells still have a roughly polyhedral shape.
At an intermediate level, some elongated nuclei can be seen (yellow arrows after moving the mouse cursor over the image or clicking on it). The elongated nuclei indicate that the cells have become flattened, forming a pavement-like arrangement.
The nuclei of the most superficial cells are more intensely stained and strongly flattened (green arrows). These cells are extremely thin and resemble tiles or scales. They are the cells that are continuously shed from the epithelial surface, a process called desquamation.
2-17 Covering epithelia
STRATIFIED SQUAMOUS EPITHELIUM – 2
At first glance, it may not be easy to see that the shape of the cells changes according to their distance from the basal layer. Look closely at the image and observe the following features:
