Search results
Results from the WOW.Com Content Network
In some tissues, a layer of columnar cells may appear to be stratified due to the placement of the nuclei. This sort of tissue is called pseudostratified. All glands are made up of epithelial cells. Functions of epithelial cells include diffusion, filtration, secretion, selective absorption, germination, and transcellular transport. Compound ...
Simple squamous epithelium falls under the physiological category of exchange epithelium due to its ability to rapidly transport molecules across the tissue layer. To facilitate this movement, some types of simple squamous epithelium may have pores between cells to allow molecules to move through it, creating a leaky epithelium. [3]
Cells of stratum corneum are sometimes without keratin and living. Examples of non-keratinized stratified squamous epithelium include some parts of the lining of oral cavity , pharynx , conjunctiva of eye , upper one-third esophagus , rectum , vulva , and vagina .
The mesothelium forms a monolayer of flattened squamous-like epithelial cells resting on a thin basement membrane supported by dense irregular connective tissue. Cuboidal mesothelial cells may be found at areas of injury, the milky spots of the omentum, and the peritoneal side of the diaphragm overlaying the lymphatic lacunae.
Another important cell type is the pulmonary neuroendocrine cell. These are innervated cells that only make up around 0.5% of the respiratory epithelial cells. [7] The ciliated cells are columnar epithelial cells with specialized ciliary modifications. The ciliated cells make up between 50 and 80 per cent of the epithelium. [8]
These cells appear to be cuboidal with a domed apex when the organ or the tube in which they reside is not stretched. When the organ or tube is stretched (such as when the bladder is filled with urine), the tissue compresses and the cells become stretched. When this happens, the cells flatten, and they appear to be squamous and irregular.
The term pseudostratified is derived from the appearance of this epithelium in the section which conveys the erroneous (pseudo means almost or approaching) impression that there is more than one layer of cells, when in fact this is a true simple epithelium since all the cells rest on the basement membrane. The nuclei of these cells, however ...
Lastly, there are three or four layers of squamous cells, with flattened nuclei. The layers of the epithelium are constantly undergoing mitosis. Basal and wing cells migrate to the anterior of the cornea, while squamous cells age and slough off into the tear film. Central thickness of corneal epithelial layer is approximately 50 to 52 μm. [2]