Connective. Tissue Structures. 



13 



-a-/- 



Fig. 5. Areolar connective tissue 

 (subcutaneous tissue) of the rabbit; 

 from an embalmed specimen: c.c, 

 connective tissue cell; w.f., bundle of 

 white fibres; y.f., yellow elastic fibre. 



concentration of the two kinds of fibres or the admixture of other 



materials. 



The commonest kind of fibrous tissue in the adult is that described 



as areolar. It is characteristic of the sub- 

 cutaneous tissue (Fig. 4) which connects 

 the skin with the body ; but areolar tissue 

 occurs also in various positions where it 

 has a similar function of joining structures 

 loosely together. Subcutaneous connective 

 tissue is a white material, the peculiar 

 appearance and properties of which are 

 due to the fact that the two kinds of 

 fibrous elements are arranged in a loose 

 felt-like network (Fig. 5). When stretched 

 it is found to yield up to a certain point, 

 beyond which it is tough and resistant. It 

 tends to regain its original shape when the 

 tension is removed. 



Fibrous connective tissue may be 

 greatly modified through the concentration 

 of either one of the fibrous elements. Con- 

 centration of white fibres is most common. 



This condition is illustrated in the thick connective tissue layer forming 



the true skin or corium (Fig. 4), but is more conspicuous in the glisten- 

 ing white tendons (Fig. 6) by which muscles are 



attached to bone surfaces, in the ligaments uniting 



bones with one another, and in the thin, broad 



aponeuroses which serve for muscular attachment. 



The structures known anatomically as fasciae are 



special sheets of connective tissue covering chiefly 



individual muscles or muscle groups. 



Fat or adipose tissue is a soft form of con- 

 nective tissue in which the cells are greatly 



enlarged and contain fatty material in the form of 



globules. It tends to occur in certain situations and 



in particular association with the bloodvessels, 



but otherwise is found in situations where areolar 



connective tissue might be expected to occur. 



Special fat masses, sometimes distinguishable by 



their darker coloration, occur at the side of the 



neck in the rabbit. In the foetus (cf . Plate VI) large 



masses of vascular connective tissue are found in 



this situation, and are probably similar in origin 



to the storing or hibernating glands of certain 



other mammals. 



Coloration or pigmentation of certain portions o£ ^e t 6 endon° ?f originTf 



of the body, especially of the skin and hairs, and the biceps muscle: m.f., 



. , , . ' K. , i 1 • ■ c ,, •-, muscle fibres ending on the 



of the retina, ciliary body, and iris of the eye, is due tendon; t., fibrous con- 

 partly to the presence of special connective tissue Zn™ tUsue ° f the ten " 



