Page 92 - Veterinary Histology of Domestic Mammals and Birds, 5th Edition

74 Veterinary Histology of Domestic Mammals and Birds

forces to which it is subjected. On this basis, connective and transient cells (e.g. lymphocytes, plasma cells). These
VetBooks.ir tissue is categorised as: are responsible for local immune responses.

Dense connective tissue (textus connectivus
· loose connective tissue (low fibre content) or
· dense connective tissue (high fibre content). collagenosus compactus)
Dense connective tissue is composed predominantly of
Loose connective tissue (textus connectivus collagen and elastic fibres, with relatively little ground sub-
collagenosus laxus) stance and smaller cell populations (fibrocytes).
Loose connective tissue is widely distributed throughout According to the functional requirements of the tis-
the body in the form of interstitial connective tissue. sue, the fibre bundles are closely apposed, their alignment
The collagen fibres are generally arranged in a grid-like corresponding with the prevailing forces of tension and
fashion, allowing the tissue to adapt to functionally deter- pressure. Dense connective tissue is more common in parts
mined changes in tension. As well as forming a flexible of the body subjected to relatively large mechanical forces.
framework (stroma) for the organs, it connects and sepa- According to the arrangement of the collagen fibres, it is
rates individual organ segments and provides channels for divided into:
nerves and vessels.
Loose connective tissue underlies epithelial tissue, from · dense irregular connective tissue and
which it is separated only by the basal lamina. It is of func- · dense regular connective tissue.
tional significance in the exchange of metabolic substances
between the capillaries and the parenchyma of organs. DENSE IRREGULAR CONNECTIVE TISSUE
The wide spaces between the collagen, reticular and Dense irregular connective tissue primarily forms the
elastic fibres facilitate intercellular transport, aided by the framework of organ capsules, fascia and aponeuroses, and
high water content of the hydrophilic glycosaminoglycans the pericardium. The perichondrium, parts of the perios-
within the abundant ground substance. In this way, loose teum (stratum fibrosum) and joint capsules are composed
connective tissue plays an important part in regulating the of sheets in which collagen fibre bundles are configured
water content of the body. in a lattice (crossing each other at various angles). This
The cells of loose connective tissue consist primarily of arrangement allows the tissue to adapt rapidly to changes
flattened fibroblasts and fibrocytes. Their shape conforms in the shape of associated tissue (e.g. distension or con-
to the course of the surrounding collagen fibres. Loose striction of a hollow organ, or contraction of a muscle).
connective tissue frequently contains histiocytes, mast cells Dense irregular connective tissue contains little ground

3.20 Longitudinal section of a tendon (pig). Dense regular connective tissue is composed primarily of collagen
fibres that are foreshortened by interspersed elastic fibres. Thus, in longitudinal section, the lightly red-staining
collagen fibres are arranged in waves. The shape of the tendinocytes (fibrocytes associated with tendons) con-
forms to the course of the surrounding fibres. Haematoxylin and eosin stain (x480).

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