NORMAL HISTOLOGY. 



occupies a corresponding space within the cement-substance, just as 

 do the cells of other dense forms of connective substances. Elastic 



fibres are almost, if not en- 

 FlG - 45- tirely, wanting in tendon. 



Elastic tissue, as usually 

 encountered as an element 

 of areolar tissue, occurs in 

 slender fibres; where, how- 

 ever, the elastic tissue be- 

 comes the dominating con- 

 stituent, as in the ligamentum 

 nuchae or ligamenta subflava 

 of man, the fibres assume 

 much greater size, becoming 

 coarse and of considerable 

 diameter. On transverse sec- 

 tion of such tissue the robust 



individual elastic fibres appear as irregularly angular or polyhedral 

 areas ; these are of variable size and held together by a small quantity 

 of areolar tissue. The fibres of elastic tissue may become broad and 

 flattened out, and so closely placed that they assume the form of a 

 reticulated elastic membrane, as Henle' s fenestrated membrane of 

 the larger arteries ; again, the 

 tissue may assume the form of a FIG. 47. 



continuous elastic sheet, as Des- 

 cemet's membrane of the cornea. 



The development of the 

 white fibrous tissue is still a 



FIG. 46. 



Primary tendon-bundles in section : b, the tendon- 

 tissue; s, interfascicular clefts occupied by granular 

 material and the tendon-cells (a) applied to the bundles. 



Elastic fibres in transverse section ; 

 from the ligamentum nuchae : a, are- 

 olar tissue separating the groups of 

 the elastic fibres ; b, the individual 

 elastic fibres in section. 



Elastic fibres closely placed, form- 

 ing the fenestrated membrane ; from 

 the aorta. 



subject of much uncertainty. It may be regarded, however, as 

 established that it is through the agency of the cells, indirect although 

 their influence may be, that the fibres of connective tissue originate. 

 Two methods are recognized in the production of the fibres. The 

 doctrine of the direct mode assumes the transformation of the eel] 



