THE PITUITARY BODY 



807 



terial may appear in them. In either case, the cells ultimately break down, setting free 

 the hyaline or granular material, which is believed to be the origin of the similar ma- 

 terial already described as existing between the neuroglial fibers of the pars nervosa 

 and therefore ultimately finding its way by the infundibulum into the third ventricle of 

 the brain. As evidence that the pituitary secretion takes this course are the facts, that 

 in the first place, the active principle of the gland may be detected in the cerebrospinal 

 fluid, and secondly, if in the living animal the infundibulum be severed close to its junc- 

 tion with the ventricular floor, a subsequent examination of the gland shows an unusual 

 accumulation of hyaline material in the stalk and adjacent portion of the posterior lobe. 

 It should be mentioned, finally, that at the margin of the intraglandular cleft the inter- 

 mediary and anterior portions of the pituitary come together, although the cells of each 

 can readily be distinguished on account of their staining properties. This pars glandu- 



Fig. 198. Drawing from a photograph of a mesial sagittal section through the pituitary gland 

 of a human fetus (5th month): a, optic chiasma; c, third ventricle; d, pars glandularis; e, iniun- 

 dibulum surrounded by epithelial cells; f, pars intermedia; g, intraglandular cleft; h, pars nervosa. 

 (Herring, from Howell's Physiology.) 



laris et intermedia also extends as a thin layer over part of the pars nervosa and around 

 the neck of the gland at the infundibulum. These relationships are well shown in the 

 accompanying diagram (Fig. 198). 



Functions 



Concerning the functions of the pituitary, it may be said in general that 

 the anterior lobe has an important relationship to the nutritive con- 

 dition of the body during growth, especially of the skeletal structures, 

 and that the posterior lobe produces a very active autacoid having to do 

 with the physiological activity of unstriped muscle fiber. The pars inter- 

 media seems to be associated with the posterior lobe in the production of 



