Structure and Functions of White Fibrous Tissue

Note: This page is part of the section about the structure and function of different Tissue Types, which is related to the section Histology and Cells (incl. structure of animal cells, cell division, mitosis, meiosis). This "Tissue Types" section is included to cover the knowledge of "Histology - The Cell" required by some courses in First-Level Anatomy and Physiology. To read about other tissue types see the links listed of on the left.

As indicated on the page about classification of (animal) tissue types, "White Fibrous Tissue" is a form of mature (rather than embryonic) connective tissue, and is one of the forms of Dense Connective Tissue. There are three (3) types of dense connective tissue.

The 3 forms of Dense Connective Tissue:

Dense Regular Connective Tissue	Dense Irregular Connective Tissue	Elastic Connective Tissue
(inelastic) also known as "White Fibrous Tissue" (due to the pale/white colour of the many collagen fibres that form its structure)	(inelastic)	(elastic)

Definition:

White fibrous tissue is connective tissue in which there is a greater proportion of white inelastic fibres than of elastic fibres. The dominance of the (white, inelastic) collagen fibres contributes to the considerable mechanical strength of white fibrous tissue.

Structure of White Fibrous Tissue:

White fibrous tissue is described in the classic text " Gray's Anatomy" as "a true connecting structure".

The main constituent of white fibrous connective tissue is the protein collagen.
White fibrous tissue is dense regular connective tissue that has a silvery white colour/appearance and is physically tough, yet pliable. It consists of fibroblasts interspersed among many collagen fibres which are often aligned in the same direction, forming a mechanically strong structure.

• Collagen fibres are also known as "collagenous fibres", "white fibres", and (in American Texts) as "collagen fibers". They range in diameter from less than 1 um (1 um = 1 micrometer = 10^-6m = 0.000001 meters ) to about 12 um.
• Fibroblast cells are widely distributed throughout connective tissues and are necessary for production of the precursors of collagen, elastic fibres, and reticular fibres (which are microscopic, non-elastic branching fibres).

Fibroblast cells (called "fibrocytes") are often found lying in rows along the bundles of (white) collagen fibres.

Functions of White Fibrous Tissue:

In general:

White fibrous tissue connects structures that require a mechanically strong bond. The main functions of white fibrous tissue involve supporting and protecting the surrounding structures.

Examples:

White fibrous tissue is an important part of many structures within the body. Its functions can therefore be identified according to the type of structure formed by a particular area of white fibrous tissue. For example, when in the form of:

• Ligaments, white fibrous tissue (in this case often with a higher proportion of elastin fibres to increase the elasticity/extensibility of the tissue with minimal compromise to the mechanical strength of the structure) attaches bones to other bones.
  
• Tendons, white fibrous tissue attaches muscles to bones and/or other structures.
  
• Membranes, white fibrous tissue protects structures within the body, including for example, organs such as the kidneys (in the case of the kidneys, through the membrane forming the capsule of the kidney).
  Note that some texts classify these tissues as "dense irregular connective tissues" because the tissue forming some membrane capsules is not arranged with as clearly repeating structure aas that found in e.g. tendons. However, although the arrangement of the tissue structures may differ, their composition (of collagen fibres and fibrocytes) is still very similar.

Locations in the body:

White fibrous (connective) tissue is present in many locations throughout the body, including skin (e.g. dermis), ligaments, tendons, cartilage and bones.

Specific examples of areas of the body in which white fibrous tissue may be found include:

• The Eyes - the sclera (of the eye) is formed of white fibrous tissue intermixed with fine elastic fibers; flattened connective-tissue corpuscles.
• The Musculo-Skeletal System - e.g. modified synovial structures, a "bursa" is a small fluid-filled sac formed from white fibrous tissue and lined with synovial membrane. This is not a part of all joints but when present provides a cushion between bones and tendons.