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Connective and supportive tissues (textus connectivus)  75



                  substance. The shape of the fibrocytes conforms to the  determined by the surrounding fibre arrangement; thus,
       VetBooks.ir  arrangement of the surrounding fibres.       they are narrow and irregularly flattened. The parallel
                                                                 bundling of collagen fibres serves to withstand forces of
                  DENSE REGULAR CONNECTIVE TISSUE
                                                                 tension.
                  Regular dense connective tissue is characterised by the   In tendons, the collagen fibrils and fibre bundles are
                  arrangement of fibre bundles in one predominant direc-  separated by layers of loose connective tissue. The inner-
                  tion. Tendons and ligaments are the principal examples of  most sheath, termed the endotendineum, is formed by
                  this tissue type. They consist mainly of collagen or elastic  tendinocytes. Groups of collagen fascicles are surrounded
                  fibres (Figures 3.20 to 3.23).                 by the peritendineum. The outer layer, or epitendineum,
                     Tendons and most ligaments are composed primar-  encloses the entire tendon (Figure 3.23).
                  ily of parallel arrays of collagen fibres enmeshed in a   Compared with other types of connective tissue, dense
                  sparse network of reticular fibres (Figure 3.20). The spaces  regular connective tissue exhibits little metabolic activity,
                  between fibre bundles contain elongated fibroblasts (ten-  with limited vascularisation of fibrous subunits. In addi-
                  dinocytes) recognisable with the light microscope by their  tion, the dense arrangement of fibres inhibits the diffusion
                  basophilic nuclei (Figure 3.20). The shape of these cells is  of nutrients.





























                  3.21  Transverse section of a tendon (pig). Dense regular connective tissue is composed of layers of collagen fibres
                  bound together by connective tissue sheaths (endotendineum, peritendineum, epitendineum). Haematoxylin
                  and eosin stain (x300).


























                  3.22  Nuchal ligament (ox). In transverse section, elastic fibres appear as isolated, yellowish clumps, surrounded
                  by a delicate network of reddish-staining fibres. van Gieson stain (x480).









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