Composition It is a pliable, mesh-like
tissue with a fluid
matrix and functions to cushion and protect body
organs.
Fibroblasts are widely dispersed in this tissue; they are irregular branching cells that secrete strong fibrous
proteins and
proteoglycans as an extracellular matrix. The cells of this type of tissue are generally connected by a gelatinous substance known as
ground substance primarily made up of collagenous and elastic fibers.
Location It may be found in tissue sections from almost every part of the body. It surrounds blood vessels and nerves and penetrates with them even into the small spaces of
muscles, tendons, and other tissues. It may likewise be present in the mediastinal extremities. Nearly every epithelium rests on a layer of areolar tissue, whose blood vessels provide the epithelium with nutrition, waste removal, and a ready supply of infection-fighting leukocytes when needed. Because of the abundance of open, fluid-filled space, leukocytes can move about freely in areolar tissue and can easily find and destroy pathogens. The areolar tissue is found beneath the
epidermis layer and is also underneath the
epithelial tissue of all the
body systems that have external openings. it makes the skin elastic and helps it to withstand pulling pain. It is also a component of the
lamina propria of the
digestive and
respiratory tracts, the
mucous membranes of
reproductive and
urinary systems, the
stroma of glands, and the
hypodermis of the skin. It is also found in the
mesentery which is surrounding the intestine.
Fibers Loose connective tissue is named based on the "weave" and type of its constituent fibers. There are three main types: •
Collagenous fibers: collagenous fibers are made of collagen and consist of bundles of fibrils that are coils of collagen molecules. •
Elastic fibers: elastic fibers are made of
elastin and are "stretchable." •
Reticular fibers: reticular fibers consist of one or more types of very thin collagen fibers. They join connective tissues to other tissues.
Areolar tissue Areolar tissue ( or ) is a common type of loose connective tissue (and the most widely distributed type of
connective tissue in vertebrates). It is so-named because its fibers are far enough apart to leave ample open space for
interstitial fluid in between (
areola is Latin for a "little open space"). It is strong enough to bind different tissue types together, yet soft enough to provide flexibility and cushioning. It exhibits interlacing, loosely organized fibers, abundant blood vessels, and significant empty space filled with interstitial fluid. Many adjacent
epithelial tissues (which are avascular) get their nutrients from the interstitial fluid of areolar tissue; the
lamina propria is areolar in many body locations. Its fibers run in random directions and are mostly collagenous, but elastic and reticular fibers are also present. Areolar tissue is highly variable in appearance. In many
serous membranes, it appears as a loose arrangement of collagenous and elastic fibers, scattered cells of various types; abundant
ground substance; numerous blood vessels. In the skin and mucous membranes, it is more compact and sometimes difficult to distinguish from
dense irregular connective tissue. ==Function==