STUDIES OX THE VASCULAR SYSTEM OF THE 

 THYROID GLAND. 



RALPH H. MAJOR. 



B'rom the Anatomicul Laboratory, Johns Hopkins University. 



With 10 Figures. 



It has long been known that the thyroid gland is a very vascular 

 organ. This we would expect both from anatomical and physiologi- 

 cal reasons, having such a rich gross blood-supply and exerting such 

 a profound influence through its secretion upon the physical and 

 nervous development of the body. Tschuewsky (1), by a series of 

 carefully performed experiments, has supplied us with data upon the 

 subject. He found that the amount of blood flowing through the thy- 

 roid per 100 gram weight of the organ to be 560 ccm. a minute. This 

 same observer, using a like standard of calculation, found the 

 amount of blood flowing through the head to be 20 ccm. per minute, 

 and through the kidney 100 ccm. per minute. Thus the thyroid, 

 according to him and using the blood-flow per gram weight as the 

 standard of comparison, is twenty-eight times as vascular as the 

 head and five and one-half times as vascular as the kidney. 

 Tschuewsky also estimates by a series of calculations that in the 

 dog the entire amount of blood in the body flows through these small 

 glands sixteen times in one day. This enormous blood-supply has 

 led to a great deal of physiological speculation and it has even been 

 suggested that the main function of the tyroid gland consists in 

 acting as a vascular shunt to protect the circulation in the brain (2). 



In these studies, begun at the suggestion of Dr. Mall and finished 

 through his constant advice and encouragment, an attempt is made 

 to study a few of the main points of the microscopic blood-supply 

 of this gland. The thyroid glands of the cat, dog and man have 

 been studied principally and the glands were those of the adult ani- 



The A>rERicAN Journal of Axatomt. — Vol. IX, Xo. 4. 



