Question

Why is the highly branched structure of reticular fibers important to creating the function of loose connective reticular tissue?

Answer 1

Reticular tissue is a special type of connective tissue that predominates in various locations that have a high cellular content. It has a branched and mesh-like pattern, often called reticulum, due to the arrangement of reticular fibers (reticulin). These fibers are actually type III collagen fibrils. In comparison to the predominant type I collagen, type III fibrils are narrower, do not form thick filaments, and have a higher content of carbohydrates. They consist of collagen molecules, each one being a trimer of three alpha-1 chains. These fibrils display a 68 nanometer (nm) banding pattern. Upon examination by transmission electron microscopy (TEM), the fibrils consist of aggregations of several transverse bands, with a distance of 68 nm between the two adjacent aggregations.

Explanation-

These types of fibers are also present in small amounts in other types of connective tissue. In fact, they are the first to develop in the structure of every tissue that contains them, highlighting their important support role. Reticular fibers support the early synthesized extracellular matrix during wound healing, scar tissue formation, and general development. As maturity or repair continues, the majority of them are replaced by the stronger type I collagen.

Some highly cellular locations containing reticular tissue include the endocrine glands, liver, bone marrow, and lymphoid organs. If you think about the structure of those tissues and organs, they all consist of heavily branching septa and internal channels. Reticular tissue also resembles a branched mesh that coincides with the path taken by those septa and channels, almost fitting them “like a glove”. Therefore, the role of the reticular scaffold is to support the cells and the small channels which travel through the respective tissues and organs. For example, in the liver, reticular tissue supports the hepatocytes and the sinusoids.

Reticular fibers are also scattered throughout various locations within the human body, but they do not form reticular tissue. These include:

• Loose connective tissue, where it intersects the epithelium
• Around adipocytes, nerves, small blood vessels, and muscle cells
• Embryonic tissue
• Hematopoietic tissues
• Lymphatic tissues (except the thymus).