MUSCLE : CONNECTIVE TISSUE. 45 



D. Connective Tissues. 



Under the name " connective tissue " are included various 

 tissues whose functions are mainly passive, and which serve to 

 support, strengthen and bind together the various organs and 

 parts of the body. Histologically the connective tissues consist 

 of elements of four kinds, united together in very varying pro- 

 portions in different situations : (1) white fibrous tissue : (2) 

 yellow elastic tissue ; (3) connective tissue corpuscles, which are 

 comparatively slightly altered cells, usually branched ; and (4) 

 ground substance, or intercellular substance. 



I. White Fibrous Tissue. This consists of a number of fine 



transparent fibres of a more or less cylindrical shape, and 

 with a very characteristic wavy outline : between the 

 fibres are connective tissue cells, usually in small num- 

 bers. The fibres are arranged side by side in bundles,, 

 and each fibre presents a number of longitudinal fibrillar 

 striations. The cellular origin of while fibrous tissue is 

 difficult to determine. The fibres are believed to be 

 formed by modification of the intercellular matrix rather 

 than from the bodies of the cells themselves. 



a. Tendon of rat's tail. Pull out a small piece of tendon 

 from the tail of a rat : place it on a slide in a drop of 

 normal salt solution : spread it out with needles, cover 

 and examine ivith low and high powers ; note : — 



i. The fibres, with wavy outlines. 



ii. The fibrillse, indicated by longitudinal wavy stria^ 

 tions within the fibres. 



Add a drop of acetic acid to the preparation : note that 



iii. The fibres swell up and become transparent. 



iv. Longitudinal rows of tendon cells, with nuclei, 

 become visible between the fibres. 



II. Yellow Elastic Tissue. This consists of fine branching 



homogeneous fibres, with great power of resisting 

 chemical reagents : the fibres are formed from an inter- 

 cellular matrix, and not from cells directly. 



a. Ligamentum nuchaB of ox. Tease finely a small shred 

 in water ; examine with low and high powers ; note : — 



