Comparison between Simple Squamous Epithelium and Stratified Squamous Epithelium MCQ - Practice Questions with Answers

Simple squamous epithelium 
Structure 

• Squamous epithelium is composed of large, polygonal flat cells whose edges fit closely together. Hence, it is also called pavement epithelium.
• The nuclei of these cells are flattened and lie at the centre of cells. 
• The cells of squamous epithelium lie on a thin basement membrane
• Location
• This type of epithelium is found in the terminal bronchioles and alveoli of the lungs, the wall of the Bowman's capsule and descending limb of the loop of Henle, membranous labyrinth ( internal ear), blood vessels, lymph vessels, heart, coelomic cavities and rete testis of the testis. 
• In blood vessels, lymph vessels and heart, it is called the endothelium. In coelom, it is referred to as the mesothelium. 
• The skin castings of frog are cast odd in single layers and are termed a squamous epithelium. 
   

Function:

• The functions of squamous epithelium are protection, excretion, gas exchange and secretion of coelomic fluid. They form the diffusion boundaries.

Stratified Squamous Epithelium

• The cells in the deepest layer are columnar or cuboidal and have oval nuclei. This layer is called stratum germinativum.
• The cells of this layer mitotically divide and give rise to new cells which shifts outward to form intermediate layers. 
• The superficial layers which are named squamous layer possess flat cells with transversely elongated nuclei. 
• Squamous layers can be of the following types:
• Keratinized stratified epithelium- The cells replace their cytoplasm with a water-impermeable protein called keratin in a process called keratinisation. These dead cells are called stratum corneum or horny layer. This layer is shed at intervals. It is found in the epidermis of skin of land vertebrates to check the water loss. 
• Non- keratinized stratified squamous epithelium- The cells of this epithelium does not have keratin and are unable to check water loss. It is present in the oral cavity, tongue, pharynx, oesophagus, lower parts of the urethra, vocal cords, vagina, cervix, the inner surface of the eyelids and cornea of the eye.