768 J. P. SIMOKDS 



The average sizes of the hypophysis have been stated as follows : 



. DIAMETER IN MILLIMETERS 



Transverse Sagittal Vertical 



Zander _ 11.9 8.0 6.55 



Schoenemann 12.5-18.0 5-6 



Thorn 12.11 6.83 5.11 



Erdheim 14.4 11.5 5.5 



Tolken 14.2 10.0 5.9 



Munson and Shaw . . . 14.1 10.5 5.6 



In the above table the average transverse and vertical diameters do 

 not show any very marked variation. The sagittal diameters, however, 

 range from 5 to 11.5 mm. In a small series of apparently normal glands 

 which I have measured, the higher figure appears to be more nearly 

 correct. 



The size and weight of the hypophysis are influenced not only by the 

 pathologic processes to which it is subject, but also by age, by pregnancy 

 and castration, and by changes in other glands of internal secretion. 

 These variations will be considered in their proper place. 



The anatomical location of the hypophysis has an important bearing 

 upon certain features of its pathology. It is inclosed by rigid, unyielding 

 bone in front, below and behind; above, it is covered with the dense dura 

 mater ; while laterally it meets the pressure from the internal carotid 

 arteries. Any enlargement of the hypophysis shows itself first in the 

 transverse and vertical diameters, and is manifested by a bulging of the 

 dura mater covering the sella turcica. LeCount has suggested that if the 

 sella becomes enlarged primarily as a result of the overgrowth of the 

 bones of the base of the skull, the hypophysis may become secondarily 

 enlarged by a process of edema ex vacuo. 



Lesions of the hypophysis may be primary in the gland itself; or they 

 may be secondary to pathologic changes in other glands of internal secre- 

 tion, or to extra-hypophyseal pathologic processes within the cranial 

 cavity. 



The "factor of safety" of the hypophysis appears to be large. In 

 many cases of tuberculosis, syphilis and embolic processes in the gland, a 

 large part of the hypophysis has been destroyed without the occurrence of 

 symptoms recognized to be due to hypopituitarism. Such cases have been 

 recorded by Simmonds(^r) (i), Merkel, and others. 



Malformations of the Hypophysis 



The hypophysis is derived from two widely separated sources, and its 

 embryologic development is a complicated process. It is not surprising 

 that congenital malformations are not uncommon, llippmann, Jakoby, and 

 Boyce and Beadles (6) have reported cases of absence of the hypophysis. 

 Bland-Sutton mentions, without giving details, a double hypophysis in a 



