ANIMAL TISSUE

       Ø  Tissue: In the body of multi-cellular animals some cells remain together and performa particular function. These cells are either formed from the ectoderm, mesoderm or endoderm of the embryo and remain close together. Inter-cellular materials or matrix are present between these cells. These cells may be similar or of different types. Arising from the embryonic cell layer when certain types of cells when remain in a particular place of the animals' body and collectively perform a common function, those cells and the inter-cellular materials or matrix secreted by them are collectively called the Tissue. That is to say, cells of a particular tissue are similar in its, origin, function and structure. The subject in which the different types of tissue are discussed is called Histology.

      Ø  Differences between Tissue and Cell:

Tissue: Originating from a same place when more than one cell with similar structure and function performs a common function, then those groups of cells are called Tissue. For example, blood is a kind 'of fluid connective tissue. In the liquid matrix or plasma of blood there are red corpuscles, white corpuscles and platelets. Blood is developed from the mesoderm of the embryo.

Cell: Cell is the structural and functional unit of tissue. For example, Red blood corpuscles (Erythrocytes), White blood corpuscles (Leucocytes) and Platelets (Thrombocytes) are various types of blood cells. Of these the red courpuscles transport oxygen and carb.on dioxide, white corpuscles take part in the defense of the body and the platelets take part in blood clotting at the site of injury and stop unwanted blood loss. Blood cells and the plasma together form the blood tissue. Blood generally takes part in the internal transportation of the body.

      Ø  Types of Tissues :

On the basis of number of cells, characteristic and the presence or absence of the intercellular materials or matrix secreted by cells, the tissue is mainly divided into four categories.

1. The Epitherlial Tissue.

2. The Connective Tissue.

3. The Muscular Tissue.

4. The Nerve Tissue.