10 TISSUES AND ORGANS 



INTESTINE 



The cytoplasm of the columnar absorbing cells is filled with 

 large numbers of very minute granules. The nucleus lies rather 

 below the middle of the cell, and the area above it may be clear, 

 but still above the nucleus. Below there is a more alveolar 

 arrangement of the cytoplasm in which lie the mitochondria and a 

 double centrosome. Still deeper the Golgi apparatus lies just 

 above the nucleus and is in the form of a wide coil. The infra- 

 nuclear area is closely packed with mitochondria. In the cells of 

 the villi these structures are collected into two masses, one at 

 each end of the cell. Their number appears to give some indication 

 as to the functional state of the cell at the time of examination. 

 Thus they are far more numerous in starvation, whereas they 

 become scantv and less thread-like after feeding. Tlie tension- 

 fibres that Heidenhain described as running through these cells 

 are now usually considered to be mitochondria. 



In connection with the so-called carcinoid tumours of the 

 appendix there has been a renewal of interest in the basal or 

 argentaffin cells of the intestine. These are usually scattered 

 about amongst the other intestinal elements. They may be 

 found in the stomach, villi, crypts, and in Brunner's glands ; even 

 in the pancreatic duct a few may be discovered. Although so 

 widely scattered and apparently small in number they have the 

 general appearances of a secretory apparatus. They are most 

 numerous in the crypts where many of them are flask-shaped, 

 usually with the narrower end at the base. When the base is the 

 widest part the distal end may taper almost to the thickness of a 

 fibril, which may or may not reach the lumen ; Masson contends 

 that the cells should be classified according to the distance to which 

 these fibrils extend. The granules in the cells show a great 

 affinity for chromium salts. Kull proposed to term them 

 " chromaffin cells," but this name is objectionable because of the 

 certainty of confusion with the quite unrelated cells of the sym- 

 pathetic nervous system. As the granules also stain well with 

 silver the name argentaffin cells proposed by Masson should be 

 adopted. The constituents of the cell that stain with silver are 

 mainly the numerous small granules, which, unlike those of the 



