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EPITHELIAL TISSUE
Part two
It is paramount to note that of all the several classifications of the epithelial tissue, the classification based on the layer of cells is 'basic'.
In the previous chapter the epithelial tissue types based on cell layers had been enumerated, futhermore each types would be discussed below;
(A). Simple epithelium: these are composed of just a single layer of cells, the shapes of these cells range from flat(squamous),cuboidal to columnar. Thus a subdivion under the above heading would include;
- Simple squamous epithelium
- Simple cuboidal epithelium
- Simple columnar epithelium
- Simple squamous epithelium: is just a single layer of flat(squamous) cells lying on a basement membrane. The layer is thin. The widht(diameter) of these cells is greater than thier respective heights. This epithelium is better suited for rapid cellular transport and diffusion thus the squamous epithelium is mostly found lining the serous pericardium of the heart, lumen of vessels(endothelium), peritoneum(mesothelium), pleura of the lungs etc.
- Simple cuboidal epithelium: is a layer of cuboidal cells lying on basement membrane. This layer is relatively thick. The width of these cell is approximately or equal to their respective heights. This epithelial type is suited for absorption, excretion and secretion. Cuboidal epithelium is mostly found lining the;
- Simple columnar epithelium: is a layer of columnar cells lying on a basement membrane. The surface of these cells may contain no surface specialization (cillia) if it does then its called 'ciliated simple columnar epithelium'.
(B). Pseudo stratified epithelium: