CONNECTIVE TISSUES 



19 



cells there is formed an intercellular material consisting of either 

 a homogeneous matrix, or, more frequently, a matrix containing 

 formed elements of a supportive nature. 



Certain types of connective tissue cells occurring in various 

 parts of the body have in common the function of phagocytosis 

 and the property of taking up and storing minute particles of 

 foreign materials brought to them in dilute colloidal solutions. 

 These cells constitute the reticulo-endothelial or macrophage 

 system and form an important constituent of the spleen, for 

 example. 



Ordinary Connective Tissues 



In the adult condition the ordinary connective tissues, with 

 few exceptions, consist of the cell basis with three kinds of fibrous 

 elements, the white, the yellow (Fig. 6) , 

 and the reticular fibres all lying in a 

 ground substance which is partly a 

 watery fluid and partly more viscid 

 in nature. White fibres are relatively 

 coarse, single, unbranched, of various 

 sizes, and of great strength, each 

 constituted by a very compact 

 bundle of fine fibrils. The yellow 

 fibres are of smaller diameter. 

 They branch and communicate, 

 but are not associated to form 

 bundles. They also differ from 



. . I'll 1 • fi^' ^- Areolar connective tissue 



white fibres m bemg highly elastic, (subcutaneous tissue) of the rabbit; 



_>, • 1 ri 1 • from an embalmed specimen: a dia- 



ine reticular fibres are less COnspiC- grammatic representation to be com- 

 pared with the photograph in Fig. 7: 



UOUS in most connective tissues, c.c. connective tissue cell; w.f., bundle 



rT->i 1 1 1 1 • ^1 of white fibres; y.f., vellow elastic fibre. 



They are related to the white fibres 



but form a close-meshed network. The tissue produced in this way 

 is known as fibrous connective tissue. It occurs in several forms 

 according to the relative concentration of the different 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 subcutaneous 

 tissue (Fig. 7) which connects the skin with the body; but occurs 

 also in various positions where it has a similar function of joining 



