THYMVS GLAND. 



89 



and consists of a sustentacular framework, lymphoid tissue, 

 the concentric corpuscles of Hassall, and blood and lymphatic 

 vessels. 



The sustentacular tissue consists of a fibrous capsule envel- 

 oping the gland, trabeculae extending inward dividing the 

 cortical portion into lobes and lobules, and a retiform frame- 

 work filling the entire organ as a basis for the lymphoid 

 tissue. 



The body of the gland consists throughout of lymphoid 



FIG. 39. 



Lobule of thym us gland (Schafer). a, cortex; tr, trabeculae; 6, bloodvessels in the 

 medulla ; c, corpuscles of Hassall. 



tissue, open and clearer in the central portion, thus constitut- 

 ing the medullary region, and dense in the outer or peripheral 

 portion forming the cortex. 



The cortical region is divided into lobes and lobules by the 

 trabeculae extending inward from the capsule. 



The lobular divisions do not extend into the medulla, 

 which thus forms a common core from which all the lobules 

 project. 



Scattered about in the medulla are the concentric corpuscles, 

 or corpuscles of Hassall, small spherical bodies having a gran- 

 ular core surrounded concentrically by flat squamous epi- 



