HYPOPHYSIS CEREBRI 573 



Function. Very little is definitely known concerning the function of 

 the hypophysis, notwithstanding extensive investigation. Much of the 

 recorded clinical and experimental data is contradictory. However, the 

 presence of the gland would seem to be essential to health, perhaps indis- 

 pensable to the maintenance of life. It appears also that its two funda- 

 mental components (anterior and posterior lobes) subserve different func- 

 tions, and that pathological alterations in the gland induce marked 

 changes in some or all of the other ductless glands, which glands appear 

 to sustain reciprocal functional relationships to each other. Absence of 

 the hypophysis (apituitarism) in mammals is associated with grave nutri- 

 tive disturbances usually leading to death. Disordered function (dyspitui- 

 tarism) is accompanied by inordinate enlargement of the extremities 

 (acromegaly) and gigantism, mental derangements, disturbances in the 

 sexual organs and improper metabolism of sugar. Reduced secretion 

 ('hypopituitarism') of the posterior lobe leads to an acquired high toler- 

 ance for sugars with the resultant accumulation of fat (Gushing; "The 

 Pituitary Body and Its Disorders," 1910). Increased secretion may be 

 responsible for some types of emaciation and for certain mental distur- 

 bances. Deficient secretion of the anterior lobe appears to inhibit com- 

 plete development of the skeleton, resulting in dwarfism and infantilism; 

 conditions of superabundant secretory activity (hyperpituitarism) are ac- 

 companied by acromegaly and gigantism (Gushing). Injection of extract 

 of the posterior lobe (pituitrin) into the blood-vessels produces a rise of 

 blood pressure accompanied by diuresis, believed to be due to a stimulation 

 of the smooth musculature of the blood-vessels. In its effect upon smooth 

 muscle, particularly of the uterus, which it stimulates to sharp and pro- 

 longed contraction, it resembles very closely the secretion of the suprarenal 

 gland. Pituitrin is now extensively used in practical medicine and espe- 

 cially in obstetrics. 



The anterior lobe is believed by some to be physiologically inactive, 

 except in cases of defective secretion of the gland, while others hold that 

 the removal of the posterior lobe gives rise to no symptoms, but that ex- 

 cision of the anterior lobe produces all the ill effects of total pituitary 

 extirpation. The contradictory results of experimental work may be due 

 to failure or inability to completely separate the several portions; more- 

 over, certain elements of the supposed symptom complex accompanying 

 hypophysectomy may be due to mechanical injury to associated parts of 

 the brain. 



Histologic Structure. The hypophysis is usually described as 

 consisting' of three portions: (1) the anterior lobe or glandular portion; 

 (2) the intermediate portion or boundary zone; and (3) the posterior 

 lobe, or nervous portion. The recent more critical investigation of 



