Types of Epithelium:
(a) Squamous epithelium : Also called pavement epithelium.
• Cells arranged end to end like tiles on a floor.
• Cells are polygonal in surface view.
• It forms the delicate lining of cavities (mouth, oesophagus, nose, pericardium, alveoli etc.) blood vessels and covering of the tongue and skin.
• Epithelial cells are arranged in many layers (stratum) to prevent wear and tear in skin. This pattern is stratified squalors epithelium.
(b) Cubical epithelium :
• They are cube like cells that fit closely, cells look like squares in section, but free surface appears hexagonal.
• It is found in kidney tubules, thyroid vesicles & in glands (salivary glands, sweat glands).
• It forms germinal epithelium of gonads (testes & ovaries).
• It involves in absorption, excretion & secretion. It also provides mechanical support.
(c) Columnar epithelium :
• Columnar means ‘pillar-like’ epithelium. It forms lining of stomach.
• Small intestine & colon, forming mucous membranes.
• Border of micro villi is present at the free surface end of each cell which increases absorption efficiency in small intestine.
(d) Ciliated epithelium :
• Cells may be cubical or columnar.
• On its free surface are present protoplasmic outgrowths called cilia.
• It helps in the movement of ova in the fallopian tube.
