8 TISSUES AND ORGANS 



fine histological observations. In post-mortem material the time 

 that elapses between the time of death and of examination is 

 sufficient to cause grave changes in the cells. With operation 

 material normal tissue is not usually available, but certainly 

 this has proved more suitable than have stomachs removed at 

 autopsy. 



The mitochondria of the gastric mucosal cells are long filaments 

 that extend from the attached end of the cell ; or perhaps Ekloff' s 

 statement is more correct, when he states that these elongated 

 mitochondria really consist of granular fragments arranged in rows. 



It is commonly recognised that the gastric glands contain two 

 types of cells, viz., peripheral and central ; usually termed parietal 

 and chief cells respectively. A third type of cell is found adhering 

 to the external surface of the epithelial tubes. The chief cells are 

 of two types ; those in the neck of the gland are mucus-secreting 

 elements, whereas those in the body of the gland are of zymogenous 

 character. It is interesting to note that the chief cells of the neck, 

 the cells of the pyloric glands and those of the cardiac glands of 

 the stomach all belong to the same type. 



The chief cells of the body of the glands are essentially zymo- 

 genous in function, and there is a distinct impression that the 

 formation of the zymogen granules is closely associated with the 

 mitochondria. The chief cells of the neck also contain secretion 

 granules, but, unlike those in the body chief cells, these are 

 almost completely translucent. Suitable methods demonstrate 

 the presence of mucin in these elements. Cells of this type are 

 not rigidly confined to the necks of the glands : they are often 

 seen scattered throughout the body of the gland. Indeed, in 

 man, whole glands, particularly in the region of the fundus of the 

 stomach, may be composed of neck cells. 



The parietal cells have been recognised for a much longer time 

 than have the chief cells ; indeed the former were for long 

 regarded as being the only cellular constituents of the glands. 

 They are most numerous in the neck of the gland, but also occur 

 under the foveolar epithelium. These cells are connected with 

 the lumen of the gland by channels passing between the contiguous 

 surfaces of the chief cells. Furthermore each one contains a 



