Histological Appearances of the Mammalian Pituitary Body 18/ 



wide limits. Different methods of fixation and staining give very diverse 

 pictures. The most useful method for showing the finer structure of the 

 pituitary body as a whole is Flemming's fixative followed by Muir's 

 eosin and methylene blue .stain. Some of the clear cells of the anterior lobe 

 occasionally seem wanting in outline, but careful staining shows that they 

 are not " Kernhaufen." Cajal's silver reduction method leaves no doubt 

 that they are cells, and their outlines are readily seen when this method is 

 employed. 



The anterior lobe of the pituitary is evidently an important glandular 

 body, and probably furnishes a secretion which passes directly into the blood- 

 vessels ; in this sense it is a blood-vessel gland, as was surmised by Ecker. 

 Its function is unknown ; extracts of it, when injected into the blood-vessels, 

 have no immediate physiological action beyond that common to most 

 glandular extracts. It is possible that this part of the pituitary has some- 

 thing to do with the regulation of the growth of the body, but in the mean- 

 time there is not evidence enough to form a basis for any definite statement. 



Structure of the Ixtermedi.\te Part of the Pituitary. 



The intermediate part of the pituitary body has its origin in common 

 with the anterior lobe. It arises from the epithelial pouch which grows 

 inwards from the buccal mucous membrane, being a development of that 

 portion of its wall which is closely applied to the nervous portion of the 

 pituitary. It is separated from the anterior lobe by the cleft throughout 

 a large part of its extent in the cat, but is continuous with it, in front 

 round the neck of the infundibulum, and behind at the posterior reflection. 

 The connection between it and the nervous portion is very intimate. 

 The portion which surrounds the neck of the infundibulum shows a 

 structure differing somewhat from the part which covers the body of 

 the posterior lobe. In the cat the epithelium surrounding the neck of 

 the infundibulum is distinctly tubular, but the lumen is not a continuous 

 one. The cells are arranged round a central lumen, which frequently 

 contains a colloid material. The tubules are continued forwards in the 

 tongue-like process already mentioned. Between them are numerous 

 large blood-vessels ; this portion of the gland is very vascular. Fig. <S 

 shows the structure of the tongue-like process of the pituitar}^ of an 

 adult cat, and its line of separation from the granular cells of the 

 anterior lobe. 



The tubules do not appear to open into the subdural space, and are 

 probably columns of cells in which lumina only appear at intervals where 

 the colloid material accumulates between the cells. In the region of the 

 anterior part of the cleft the tubules .sometimes appear to open into the 

 latter, but their lumina are frequentl}^ interrupted. Colloid material has 

 been noted by many observers in the cleft, and may enter it in this 



