Histology investigates tissue structures of animals and plants, and how the tissues are organized to form organs. The tissues are composed of cells and an extracellular matrix surrounding them. Numerous cell types have been recognized, and the cells of one particular tissue usually include more than one cell type. Some cells also wander inside the body, for example, in the blood and the lymph.
Although our body is a rather complex system, it is composed of the following four basic types of tissue:
2. connective tissue,
3. muscular tissue,
4. nervous tissue.
These tissue do not exist as isolated units. but in association with each other in diverse proportions, making up different organs.
A basic method to obtain histologic knowledge is microscope which is a versatile tool for visualization of the tissue fine structures. Additional information is provided by the use of various staining techniques to demonstrate the structures of interest. For instance, several chemical dyes that bind to specific structures or molecules can be used for staining.