A second type of embryonic connective tissue forms in the umbilical cord, called mucous connective tissue or WhartonвЂ™s jelly. Clusters of mesenchymal cells are scattered throughout adult tissue and supply the cells needed for replacement and repair after a connective tissue injury. The first connective tissue to develop in the embryo is mesenchyme, the stem cell line from which all connective tissues are later derived. Embryonic Connective TissueДЄll connective tissues derive from the mesodermal layer of the embryo (see ). Adipose cells store surplus energy in the form of fat and contribute to the thermal insulation of the body. Transport of fluid, nutrients, waste, and chemical messengers is ensured by specialized fluid connective tissues, such as blood and lymph. Specialized cells in connective tissue defend the body from microorganisms that enter the body.

Protection is another major function of connective tissue, in the form of fibrous capsules and bones that protect delicate organs and, of course, the skeletal system. Functions of Connective TissuesД¬onnective tissues perform many functions in the body, but most importantly, they support and connect other tissues from the connective tissue sheath that surrounds muscle cells, to the tendons that attach muscles to bones, and to the skeleton that supports the positions of the body. The amount and structure of each component correlates with the function of the tissue, from the rigid ground substance in bones supporting the body to the inclusion of specialized cells for example, a phagocytic cell that engulfs pathogens and also rids tissue of cellular debris. Connective tissues come in a vast variety of forms, yet they typically have in common three characteristic components: cells, large amounts of amorphous ground substance, and protein fibers. This ground substance is usually a fluid, but it can also be mineralized and solid, as in bones. The major component of the matrix is a ground substance often crisscrossed by protein fibers. The matrix plays a major role in the functioning of this tissue. The matrix usually includes a large amount of extracellular material produced by the connective tissue cells that are embedded within it. Unlike epithelial tissue, which is composed of cells closely packed with little or no extracellular space in between, connective tissue cells are dispersed in a matrix. Explain the functions of connective tissuesДЄs may be obvious from its name, one of the major functions of connective tissue is to connect tissues and organs.Identify and distinguish between the types of connective tissue: proper, supportive, and fluid.By the end of this section, you will be able to:

Index of essential anatomy 3