Physiology, Physiological Chem- 

 istry and Experimental Pathology 

 of the Pineal Gland 



CAREY P. McCORD 



CINCINNATI 



The Pineal Problem, Past Views and Present Aspects 



The evidence that indicates for the pineal body a glandular function 

 is much less definite than for such glandular organs as the thyroid, hy- 

 pophysis, parathyroids and suprarenals. 



Doubt is frequently expressed that the pineal body is more than a 

 functionless vestige of what was once, in earlier evolutional stages, a func- 

 tioning eye. Certain observations have led to the contention that the pineal 

 body, through metamorphosis, has become a highly specialized tissue that 

 serves the body in a manner comparable, with the major members of the 

 endocrin system. 



Although the pineal forms a portion of the roof of the third ventricle, 

 it is essentially a detached portion of the brain. A recognition of this 

 fact is necessary to appreciate the early physicians' conception of its 

 function. To them the structure was a movable organ, standing guard 

 between the third and fourth ventricles, serving as a valve to control the 

 flow of fluid from the brain to the spinal cord. However, so early an 

 observer as Galen conceived a function of the pineal other than a mechan- 

 ical one, for he writes: "It is in substance glandular and was devised 

 for the same purpose as the other glands of the body." 



Morphologic studies have been prosecuted in the main to determine: 



( 1 ) the presence of glandular tissue, presumptive of a secretory function ; 



(2) the presence of contractile tissue, supporting the view that this organ 

 is a valve regulating the flow of cerebrospinal fluid; (3) nerve fiber com- 

 munication between this organ and other portions of the brain, and (4) 

 evidence of involution changes in the gland, indicative of a cessation or 

 lessening of function. 



The chief stimulus leading to systematic experimental investigations 

 to ascertain the functions of the pineal gland as a factor in normal growth 



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