Connective tissue (CT) is one of the four types of biological tissue that supports, connects or separates different types of tissues and organs in the body. It develops from the mesoderm. The other three types are epithelial, muscle, and nervous tissue. Connective tissue is found in between other tissues everywhere in the body, including the nervous system. In the central nervous system, the three outer membranes (the meninges) that envelop the brain and spinal cord are composed of connective tissue.
All connective tissue consists of three main components: fibers (elastic and collagenous fibers),ground substance and cells. (Not all authorities include blood or lymph as connective tissue.) Blood and lymph lack the fiber component. All are immersed in the body water.
The cells of connective tissue include fibroblasts, adipocytes, macrophages, mast cells and leucocytes.
Connective tissue can be broadly subdivided into connective tissue proper, and special connective tissue.Connective tissue proper consists of loose connective tissue and dense connective tissue (which is further subdivided into dense regular and dense irregular connective tissues.) Special connective tissue consists of reticular connective tissue, adipose tissue, cartilage, bone, and blood. Other kinds of connective tissues include fibrous, elastic, and lymphoid connective tissues. New vascularised connective tissue that forms in the process of wound healing is termed granulation tissue.Fibroblasts are the cells responsible for the production of some CT.