Connective tissues bind structures together, form a framework and support for organs and the body as a whole, store fat, transport substances, protect against disease, and help repair tissue damage. They occur throughout the body. Connective tissues are characterized by an abundance of intercellular matrix with relatively few cells. Connective tissue cells are able to reproduce but not as rapidly as epithelial cells. Most connective tissues have a good blood supply but some do not.
Numerous cell types are found in connective tissue. Three of the most common are the fibroblast, macrophage, and mast cell. The types of connective tissue include loose connective tissue, adipose tissue, dense fibrous connective tissue, elastic connective tissue, cartilage, osseous tissue (bone), and blood.

Fibroblast
A connective-tissue cell of mesenchymal origin that secretes proteins and especially molecular collagen from which the extracellular fibrillar matrix of connective tissue forms.

Macrophage
A phagocytic tissue cell of the reticuloendothelial system that may be fixed or freely motile, is derived from a monocyte, and functions in the protection of the body against infection and noxious substances -- called also histiocyte.

Mast Cell
A large cell that occurs especially in connective tissue and has basophilic granules containing substances (as histamine and heparin) which mediate allergic reactions.

Referrence:Connective Tissue(Chinese Version)