0.2 Histology module 4a and 4b: connective tissue  (Page 2/30)

Connective tissue proper

Fibroblasts are present in all connective tissue proper ( [link] ). Fibroblasts and adipocytes are fixed cells, which means they remain within the connective tissue. Other cells, such as mast cells move in and out of the connective tissue in response to chemical signals.

Connective tissue proper

Cell types

The most abundant cell in connective tissue proper is the fibroblast    .Proteoglycans and proteins secreted by fibroblasts combine with extra-cellular fluids to produce a viscous ground substance that, with embedded fibrous proteins, forms the extra-cellular matrix. As you might expect, a fibrocyte    , a less active form of fibroblast, is the second most common cell type in connective tissue proper.

Connective tissue fibers and ground substance

Three main types of fibers are secreted by fibroblasts: collagen fibers, elastic fibers, and reticular fibers. Collagen fibers , while flexible, have great tensile strength, resist stretching, and give ligaments and tendons their characteristic resilience and strength. These fibers hold connective tissues together, even during the movement of the body.

Elastic fiber contains the protein elastin. The main property of elastic fibers are that after being stretched or compressed, it will return to its original shape. Elastic fibers are prominent in elastic tissues found in skin and the elastic ligaments of the vertebral column and the outer ear.

Reticular fiber is also formed from the same protein subunits as collagen fibers; however, these fibers form a branching network. They are found throughout the body, but are most abundant in the reticular tissue of soft organs, such as liver and spleen, where they anchor and provide structural support

Loose connective tissue

Loose connective tissue is found between many organs where it acts both to absorb shock and bind tissues together. It allows water, salts, and various nutrients to diffuse through to adjacent or imbedded cells and tissues.

Adipose tissue consists mostly of fat storage cells, with little extracellular matrix ( [link] ). White fat contributes mostly to lipid storage and can serve as insulation from cold temperatures and mechanical injuries. Adipose tissue can be found protecting the kidneys and cushioning the back of the eye. It is also found directly beneath the skin.

Adipose tissue