PATHOLOGICAL ANATOMY AND HISTOLOGY 773 



Edema. Edema of the hypophysis is not easily detected because of 

 the slight amount of connective tissue of the anterior lobe and because of 

 the normal looseness of the structure of the neurohypophysis. Thaon(&) 

 asserts that the hypophysis has no lymph vessels. If this be true, it is 

 possible that edema of the hypophysis does not occur. 



Thrombosis. The formation of thrombi in the vessels of the hypophy- 

 sis is of relatively rare occurrence. In many of the wide vessels of 

 the anterior lobe, one frequently sees bluish or pink staining masses of 

 homogeneous material, with or without accompanying red blood cells. 

 These appear to be intravascular colloid. In one of my specimens, how- 

 ever, there were three small vessels in one part of the anterior lobe which 

 contained purplish masses showing a filamentous network like fibrin, the 

 whole mass closely resembling a thrombus. There were no changes in 

 the adjacent cells. Merkel has observed a thrombus in a vessel of the 

 anterior lobe due to an embolus of metastatic tumor cells. Simmonds(^) 

 has also observed thrombosis in the vessels of the hypophysis. 



Embolism and Infarction. Benda(fr) (c) has made a careful study of 

 the blood supply of the human hypophysis. The gland is supplied with 

 blood from three paired sources. One pair of vessels, previously described 

 by Luschka, passes from the internal carotid artery to the infundibulum, 

 and, turning downward, probably supplies the pars intermedia. A second 

 branch, on each side, leaves the internal carotid artery at its entrance into 

 the sinus cavernosus ; this small vessel goes to the groove between the two 

 lobes and enters the anterior lobe at about the middle of its poster o-lateral 

 border. There are also fine branches from the pia mater to each side of 

 the infundibulum. These findings of Benda have been confirmed by 

 Simmonds(^) and Schmorl. The blood supply of the human hypophysis 

 appears to differ from that of the dog as described by Dandy and 

 Goetsch. 



The arteries which supply the anterior lobe of the hypophysis differ 

 from those which go to the neurohypophysis in this important respect, 

 that they are functional end-arteries while those that supply the posterior 

 lobe anastomose freely. Hence, emboli which lodge in branches to the 

 anterior lobe cause infarcts, while those which are stopped in vessels of 

 the posterior lobe are without effect, unless they contain bacteria or tumor 

 cells. In such event an abscess or a metastatic tumor develops in the 

 neurohypophysis. In more or less complete infarction of the anterior 

 lobe of the hypophysis the infundibulum and pars intermedia may remain 

 intact because they receive a separate blood supply through blood vessels 

 which run upon and in the infundibulum from the pia mater. 



Embolism and infarction in the hypophysis are not uncommon occur- 

 rences. Simmonds(/) found embolic processes 20 times in 1,500 hypophy- 

 ses, from all sources, examined. Infarcts of the anterior lobe have also been 

 observed by Merkel, Schmorl, Schmidtmann, Benda (c), Berblinger(c), 



