Tissue

For other uses, see Tissue (disambiguation).

A Tissue forms part of an organ in plants or animals. Tissues are groups of cells that work together to do a job in the body. They are a group of cells having the same origin, structure and function. The cells look the same or almost the same. The work the cells in a tissue do is the same or almost the same.

Cross-section of a flax plant stem with several layers of different tissue types:
1. pith
2. protoxylem
3. xylem
4. phloem
5. sclerenchyma (bast fibre)
6. cortex
7. epidermis

The four main kinds of tissue in animals are:

1. connective tissue
2. muscles
3. nerves
4. epithelial tissue

Organs are made up of more than one kind of tissue. The heart is an organ. It is made up of different tissues. It has muscle tissue called myocardium. It has connective tissue on the inside (endocardium), and on the outside (pericardium). The heart has valves that make sure the blood goes the right way through the heart. So the heart is an organ made from several tissues.

The study of the structure of tissues under a microscope is called histology.