496 



TEXT-BOOK OF PHYSIOLOGY 



bk d 



f 



arranged in columns between which pass large thin-walled blood-vessels 

 In view of the physiologic importance of this lobe it is believed that the 

 granules of the cell represent an internal secretion, which passes into the 

 blood-stream and is thus distributed to various regions of the body. 



The pars intermedia consists of several layers of finely granular epithelial 

 cells which develop a colloid material that subsequently passes into the pos- 

 terior lobe where it becomes hyaline in character. The epithelial investment 

 is separated from the posterior lobe by a layer of blood-vessels though 

 columns of cells penetrate it. 



The posterior lobe consists of neuroglia cells and fibers. True nerve- 

 cells are apparently wanting. Throughout the lobe there are numerous small 

 hyaline bodies which are apparently streaming upward to the ventricular 

 cavity. In view of the physiologic importance of this infundibular body or 

 pars nervosa, these hyaline masses are believed to represent an internal secre- 

 tion which passes upward through loose tissue channels toward the infundi- 

 bulum to be discharged into the fluid of the third ventricle. If the stalk be 

 divided there is an accumulation of these bodies in the posterior lobe. 

 Both parts of the pituitary are well supplied with blood though from different 

 sources. 



Effects of Total Removal. The effects which were observed by the 

 earlier investigators to follow total removal of the hypophysis were not 

 always in accord by reason of the difference in the operative methods 



pursued, injuries to the brain, 

 infections, imperfect removals 

 as shown by post-mortem ex- 

 amination, etc. Some inves- 

 tigators claimed that after total 

 removal animals lived for long 

 periods and that therefore the 

 gland was not essential to life; 

 others claimed, however, its 

 total removal was followed very 

 shortly by death preceded by a 

 series of characteristic symp- 

 toms and that therefore it was 

 absolutely essential to life. 

 The introduction of a new 



method of procedure for the re- 



FIG. 224. MESIAL SAGGITAL SECTION OF THE PIT- , f f , hvnnnhv;i<; hv 



UITARY BODY OF THE MONKEY, a, Optic chiasm; b, moval ol tfte . nypopliysis 



process of the pars intermedia; c, third ventricle; d, PaulesCO and its employment 



anterior lobe proper;/, posterior lobe or pars nervosa; by Gushing and his CO-WOrkers 



i, epithelium investment of the posterior lobe; ,epithe- , J i j 4. u i,- u 



lium of the pars intermedia passing over the neighbor- h as led to results which are for 



ing brain mass; e, cleft. (After Herring.} the most part in general agree- 



ment. This method involves 



an approach to the gland through the temporal bone instead of through the 

 buccal cavity as was formerly the case. The temporal muscles are first 

 dissected away from the skull on both sides and reflected downward. 

 Large openings are made in the bone and dura of both sides. The temporal 

 lobe on one side is lifted up with a spoon-shaped spatula sufficiently large 

 to expose the hypophysis, hanging from the infundibulum. Owing to the 



