67 — 



Lesson XVII. 



SIMPLE ADENOID TISSUE. THYMUS, 

 LYMPH GLAND, AND SPLEEN. 



(a) Simple or Diffuse Adenoid Tissue. 



A juMtion of the vennifdnii niipeiidix of ;i riihhit was liardeiied 

 ill absolute alcoliol, stained in borax (;arniine, embedded in paraffin, 

 and cross-sttftioned. Fix to the sli<le, and nionnt in balsam. 



Examine under high power. The mucosa and sub- 

 mucosa form a continuous zone of adenoid tissue. The 

 mass of round cells are so closely packed that they cover 

 up the adenoid reticulum in which they are found. Sketch 

 as seen under high power. 



(b) TonsiL 



Tiip tonsil of a dog was hardened in mercuric chloride, stained 

 in Delafield's lipematoxylin, embedded in paraffin, and sectioned. 

 Fix and mount in balsam. 



Study first under low power. Under the stratified 

 pavement epithelium are found a number of round or oval 

 nodules of adenoid tissue embedded in diflfuse adenoid tis- 

 sue. They are more or less completely sei)arated from the 

 surrounding tissue by a fibrous tissue envelope. Under 

 high power it will be noticed that in many places cells from 

 the adenoid tissue have wandered into the epitlielium, often 

 to such an extent that it is difficult to recognize the epithe- 

 lial cells. One or more small mucous glands are often seen 

 in sections of the tonsil. Sketch under low power. 



(c) Thymus Gland. 



The thymus gland of a new-born mammal was hardened in 

 mercuric chloride, stained in Delafield's hiematoxylin, embedded in 

 parafiin, and sectioned. Fix and mount in balsam. 



Study under low power. The gland is divided into 



