BLOOD SUPPLY OF THE PITUITARY BODY 149 



The circulation of the ^^ parahypophysis'^ 



As has been stated in discussing methods, after the injections 

 were made a block of tissue containing the gland within its in- 

 tact meningeal envelopes was removed and cleared in glycerine. 

 On examining the base of the cleared specimen with the bino- 

 cular dissecting microscope, a minute button-like structure (figs. 

 1 and 3) was seen lying below the mid-point of the gland and be- 

 tween the two layers of the dura which originally lined the base 

 of the sella turcica. This structure had been previously observed 

 in a number of the serial longitudinal sections which had been 

 made as a routine after all of the experimental pophyhysectomies. 

 No especial importance had been attached to it and it naturally 

 had escaped histological observation in all of the cases in which 

 the dura had not been removed and sectioned together with the 

 gland. It is an epithelial body and appears to be an organ which 

 is invariably present and one which may have some physiological 

 significance. It contains under normal conditions none of the 

 typical anterior lobe (eosinophilic) cells. A minute median pit 

 in which the body rests is usually discernable in the centre of the 

 sella turcica after the removal of its lining dura. 



This epithelial body has a separate circulation distinct from the 

 others which have been described (fig. 3). The arterial supply 

 seems to be of two-fold origin. A minute artery enters the gland 

 posteriorly, and by reconstruction of two specimens its origin 

 can be traced by a relatively long intradural course to each pos- 

 terior lobe artery, the two uniting into a single trunk before reach- 

 ing the parahypophysis. Moreover the small intradural branch 

 from each internal carotid artery gives an additional bilateral 

 arterial supply. A single small vein cares for the return flow. 

 This vein apparently passes into the bone at the situation of the 

 above mentioned pit, though it is probable that there may also be 

 a connection in the dura with the network of venous channels, 

 which are somewhat radially arranged around the parahj^pophysis. 

 This structure therefore should retain its circulation intact in 

 procedures similar to the experimental hypophysectomies in which 



THE AMERICAN JOURNAL OF ANATOMY, VOL. 11, NO. 2 



