VAN 211: Veterinary Histology and Embryology (2+2)

DENSE CONNECTIVE TISSUE

• Here fibres are closely packed to form sheets, cords or bands (e.g dermis, capsules of certain organs, aponeurosis, ligaments and tendon) based on the nature of arrangement of the fibres.
• They are classified into two groups
  • Irregularly arranged
  • Regularly arranged
• Dense irregularly arranged connective tissue occurs in the form of sheets. Main component a coarse collagenous tissue but elastic and reticular are also present.
• The fibres interlace to form tough feltwork. Fibroblasts and macrophages are present. (e.g dermis of the skin, periosteum, perichondrium and capsules of some organs).
• Dense regularly arranged connective tissue occurs in the form of cordlike or band like structures.
• Fibres are arranged parallel to one other (e.g tendons, ligaments and aponeurosis).
  • Tendons are composed almost only of white fibrous tissue. Fibres are densely packed in parallel bundles. Fibroblasts alone are present in small numbers. These are called tendon cells. The tendon cells are quadrangular and so highly flattened that in profile they appear as thin linear structures. They occur between tendon bundles around which they have extensions.
  • Aponeuroses have same structure as tendons but are broad sheets. Fibres run in superimposed layers those of one layer at an angle to adjacent layers. The layers may interweave.
  • Ligaments are predominantly of white fibrous tissue but a few are composed entirely of elastic fibres. The yellow elastic ligaments are formed of parallel coursing yellow fibres, bound together by small amount of areolar tissue (e.g. ligamentum nuchae where elastic fibres are very large and ligaments flava).