PITUITARY BODY 645 



A further subdivision of the epithelial portion is made into the 

 anterior lobe proper and the pars intermedia or intermediate lobe, con- 

 sisting of epithelial cells, less granular and less richly supplied with 

 bloodvessels than those of the pars anterior. The pars intermedia 

 forms an epithelial investment of the pars nervosa, almost completely 

 surrounding it and throwing out offshoots of epithelial cells into its 

 substance, which is also invaded by colloid material secreted by the 

 cells of the intermediate lobe. The differences in the structure of the 

 anterior and posterior lobes of the pituitary body correspond to a 

 difference in their development. The anterior lobe is developed (in 

 man in the fourth week of intra-uterine life) from an ectodermal pouch 

 (Rathke's pouch), which is pushed up from the roof of the bucco- 

 pharyngeal cavity towards the mid -brain. The posterior lobe is 

 developed from an extension of the neural ectoderm, which grows back- 

 wards as the infundibular process till it meets and blends with that 

 portion of the buccal pouch which gives rise to the pars intermedia. 

 The pars intermedia is separated from the anterior lobe proper by a 

 cleft which represents what is left of the lumen of Rathke's pouch. 

 In connection with the interpretation of the results of experiments on 

 removal of the pituitary body, it is of consequence to remember that 

 a residue of the same epithelium which develops into the anterior lobe 

 appears always to get cut off in the vault of the pharynx, constituting 

 the so-called pharyngeal hypophysis, and consisting of a cord of cells 

 identical with those of the anterior lobe (Haberfeld). Embryonic 

 ' rests ' of hypophyseal tissue are also often found in the dura of the 

 sella turcica, in which the pituitary body lies, and in the body of the 

 sphenoid bone. Cells of the intermediate lobe also run up the stalk 

 of the infundibulum, and even stretch for a little distance along the 

 floor of the third ventricle. Add to this the formidable nature of the 

 operations required for the extirpation of the hypophysis from its 

 sheltered position within the skull, and it will not be wondered at that 

 complete harmony has not been attained as to the consequences of its 

 removal. The best evidence at present is to the following effect: 



(When the pituitary body is completely removed, death speedily 

 and invariably ensues, in dogs, on the average within twenty-four 

 to forty-eight hours.) Puppies often live as long as two or three 

 weeks. The much longer periods of survival occasionally witnessed 

 are due to failure to remove some small portion of the hypophyseal 

 epithelium. On the day after the operation the animals may be 

 able to walk about, to eat and drink, and may show an interest in 

 their surroundings. The temperature, pulse, and respiration at 

 this time may be normal. Soon, however, they become lethargic, 

 then comatose, with characteristically incurved spine, slow respira- 

 tion, with long-drawn inspiration, a feeble pulse, perfectly limp 

 muscles, and often a subnormal temperature, and the appearance 

 of sugar in the urine. This deep coma passes into death, with no 

 perceptible transition, and without a struggle (Paulesco, Gushing). 

 The ablation of a part of the cortical substance of the anterior 

 (epithelial) lobe of the hypophysis is compatible with permanent 

 survival, and gives rise to no symptom of disorder. The same is 

 true when only the posterior lobe is removed. This does not seem 

 to be followed by any recognizable symptoms. In some animals, 



