1909.] 



The Functions oj the Pituitary Body. 



465 



when associated, as these symptoms often are in acromegaly, with tumours 

 of the pituitary, they have not been usually ascribed to an increased activity 

 of that gland.* Indeed, in many cases of acromegaly, polyuria does not 

 occur. Doubtless this is due to the hypertrophy and increased activity 

 being confined to the anterior lobe, which is the part usually involved in 

 this disease. Often it does not occur until the disease is more advanced, 

 and may then be due either to the hypertrophy involving the pars 

 intermedia or to this part being stimulated mechanically by the adjacent 

 growth. 



Conclusions. 



1. The pituitary body consists of three parts : (1) the pars anterior, 

 formed of vascular glandular epithelium ; (2) the pars intermedia, formed of 

 a less vascular epithelium secreting " colloid " ; (3) the pars nervosa, 

 consisting mainly of neuroglia, but invaded by the colloid of the pars 

 intermedia, which passes through it into the infundibulum of the third 

 ventricle. These parts differ from one another in function. 



2. The function of the pars anterior is probably related to growth of 

 the skeletal tissues, including cartilage, bone, and connective tissue in 

 general. The chief evidence in favour of this is derived from the fact that 

 hypertrophy of the pars anterior is associated with overgrowth of the skeleton 

 and of the connective tissue in growing individuals, and of the connective 

 tissues especially in individuals in whom growth has ceased. These effects 

 are probably produced by hormones. 



3. The function of the pars intermedia is to produce a " colloid " material 

 which contains active principles or hormones acting upon the heart, blood- 

 vessels, and kidneys. Probably there are several such hormones acting upon 

 blood-vessels and kidneys independently, and also acting antagonistically ; so 

 that according to circumstances either a rise or fall of blood-pressure, an 

 increased or diminished secretion of urine, may be produced, and the effects 

 on the kidney may be independent of those on the blood-vessels. The 

 hormones, which appear to be most active are those which produce contraction 

 of the blood-vessels in general, with dilatation of the renal vessels and 



* Eosenhaupt (1903), who describes a tumour of the pituitary associated with poly- 

 uria, states that he is " loth to assume that this is due to the pituitary tumour, since 

 there are no physiological grounds to support such a view." Arid Steinberg (1897) 

 remarks that in the " die alte Casuistik " it was not uncommon to associate pituitary 

 tumours with polyuria and glycosuria, but that it is more probable that the latter 

 symptoms are due to an overlooked condition of acromegaly. More recently, Borchardt 

 (1908) has suggested that the glycosuria which is so often recorded in acromegaly may be 

 associated with the hypertrophy of the pituitary, but does not especially connect it with 

 the pars intermedia. 



