THE CONNECTIVE TISSUES. IOI 



reticulum has the appearance of a network composed of branched 

 and anastomosing cells. 



Reticular connective tissue is found in adenoid tissue and lymph- 

 glands, in the spleen, and in the mucous membrane of the intestinal 

 canal, and in these locations the meshes of the reticulum are filled with 

 lymph-cells and other cellular elements, which, unless removed, 

 obscure the reticulum. Connective -tissue fibrils giving the same 

 reaction as those found in the adenoid reticulum are found associ- 



Fig. 63. Reticular fibers from a thin section of a lymph-gland, digested on the 

 slide in pancreatin and stained in iron-lac-hematoxylin. 



ated with white and elastic fibers in the liver, kidneys, in the lung, 

 and in many other tissues. In bone-marrow a reticulum is found, 

 in the meshes of which are the cellular elements of this tissue. 



3. FIBROUS CONNECTIVE TISSUE, 



Fibrous connective tissue can be divided morphologically into 

 two groups : In one the bundles of fibers cross and interlace in 

 all directions, forming a network with meshes of varying size 

 formless or areolar connective tissue. In the other the bundles of 

 fibers are parallel to each other, as in tendon and many of the apo- 

 neuroses and ligaments, or less regularly arranged, yet very densely 

 woven, as in fascias, the dura mater, and the firm, fibrous capsules 

 of some of the organs. 



(a) In areolar connective tissue the bundles of white fibers, 

 which vary greatly in size and which often divide and anastomose with 

 portions of other branching bundles, intercross and interlace in all 

 directions. If the bundles of fibers are numerous, the interlacement is 

 more compact, thus forming a dense areolar connective tissue ; if less 

 numerous, the network is more open, as in loose areolar connective 

 tissue. Elastic fibers are always found in areolar connective tissue, 

 though in varying quantity. They anastomose to form a network 

 with large, irregular meshes, and run on or between the bundles of 

 white fibers. The meshes between the bundles of fibers, and the 



