Page 93 - Veterinary Histology of Domestic Mammals and Birds, 5th Edition

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).

Vet Histology.indb 75 16/07/2019 14:55