Tissue
A tissue is a collection of cells that work together to perform certain tasks and typically share an embryonic origin. Four fundamental categories can be used to categorize animal tissues based on their form and function. 1. Epithelial Tissue The cells that make up the membranes that line and cover the body's surfaces, as well as the glands that are formed from these membranes, make up an epithelial tissue or epithelium. There is some intercellular space between epithelial cells since they are densely packed and kept together by numerous cell connections. Because it does not have its own blood supply, epithelial tissue is avascular. Epithelial tissue plays many roles such as protection, filtration, secretion, absorption and excretion. Cell shapes: There are 3 basic shapes - Squamous cells are arranged like floor tiles and are thin Cuboidal cells are as tall as they are wide and are shaped like cubes or hexagons Columnar cells are much taller than they are w...