FIBROUS TISSUE: 49 



parts of this layer which are to form connective tissue, the embryonic 



FIG. 55. JELLY OP WHARTON. (Kanvier.) 



r, ramified cells intercommunicating by their branches ; I, a row of lymph cells ; 

 /, fibres developing in the ground-substance. 



cells become separated from one another by a muco-albuminous semi 

 fluid intercellular substance (ground-substance), but the cells generally 

 remain connected by their 

 processes. The connective- 

 tissue fibres, both white 

 and elastic, are deposited in 

 this ground-substance, the 

 elastic substance usually in 

 the form of granules (fig. 

 56, g), which subsequently 

 become connected together 

 into elastic fibres or laminae, 

 as the case may be, the 

 white fibres appearing at 

 first in the form of very 

 fine bundles, which after- 

 wards become gradually 

 larger; so that in fibrous 

 tissue the whole ground-substance is eventually pervaded by them, and 

 the cells of the tissue become squeezed up into the intervals between 

 them. Before any considerable development of fibres has taken place, 

 the embryonic connective tissue has a jelly-like appearance ; in this 

 form it occurs in the umbilical cord, where it is known as the jetty of 

 Wlmrton (fig. 55). 



FIG. 56. DEVELOPMENT OF ELASTIC TISSUE BY 

 DEPOSITION OF FINE GRANULES. (Ranvier.) 



, fibres being formed of rows of ' elastin ' granules ; 

 p, flat plate-like expansion of elastic substance 

 formed by the fusion of ' elastin ' granules. 



