238 NORMAL HISTOLOGY AND ORGANOGRAPHY. 



vein are formed on each side. Extensive lymphatics 

 accompany the blood system. The nerves are derived 

 from the middle and inferior cervical ganglia of the 

 sympathetic. They accompany the blood-vessels, 

 whose walls they innervate, sending also branches 

 that extend close to the base of the epithelial cells. 



PARATHYROIDS. 



The parathyroids are two flattened bodies, one- 

 fourth to one-half inch in diameter, that are con- 



atA'^'Vj;^: 



W?i& 



Fig. 183. From parathyroid of man (Huber.) 



stantly present and placed in close proximity to the 

 upper and posterior surface of the lobes of the thy- 

 roid gland. They consist of solid masses of epithelial 

 cells. Lymphoid follicles are usually closely asso- 

 ciated with these masses. The function of these 

 little bodies is not known; however, if the thyroid 

 gland be removed and the parathyroid left, the effect 

 of a complete thyroidectomy is not obtained. 



