Loose connective tissue is the most common type of connective tissue in vertebrates. It holds organs in place and attaches epithelial tissue to other underlying tissues. It also surrounds the blood vessels and nerves. Cells called fibroblasts are widely dispered in this tissue; they are irregular branching cells that secrete strong fibrous proteins and proteoglycans as an extracellular matrix.

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 join connective tissues to other tissues.