CONNECTIVE TISSUES 



37 



The fibres are extremely fine ; they are not usually arranged 

 in bundles, but form a delicate network which permeates the 

 ground substance in every direction. In the very immature types 

 the fibres are all of the white fibrous variety ; fine elastic fibres 

 appear later. The fluid ground substance forms an abundant mass 

 of tissue juice which occupies the meshes of the fibrous net. 



Gelatinous connective tissue (mucous or mucoid connective tis- 

 sue) occurs only in the umbilical cord, where it forms the " jelly 

 of Wharton," and in the vitreous humor of the eye. Its semifluid 



FIG. 39. GELATINOUS CONNECTIVE TISSUE FROM TUB UMBILICAL CORD OF A MEW-BORN 



INFANT. 



Safrauin and water blue, x 410. 



ground substance is of a gelatinous consistence, and forms the 

 greater portion of the tissue; in the vitreous humor there is 

 little else. 



The cells are mostly of the branched lamellar variety, are few 

 in number in the vitreous, but more abundant in the umbilical 

 cord. In the vitreous humor, also, there are very few fibres ; those 

 which are present are very fine, and form a delicate reticulum. In 

 the umbilical cord the fibres are more abundant, and possess a 

 tendency to form bundles, which are disposed in parallel cylin- 

 drical layers around the large blood vessels. 



Areolar connective tissue (Fig. 34) is the most widely distributed 

 of all the varieties ; it fills all otherwise unoccupied spaces within 



