254 THE DUCTLESS GLANDS 



B. The Coccygeal Body 



The coccygeal body in the human subject is a small organ, at 

 most 2-5 millimetres in diameter, sometimes broken up into a 

 number of smaller bodies, placed immediately in front of the 

 apex of the coccyx, and receiving branches of the middle sacral 

 artery. 



The body was discovered by Luschka in 1860, and since that 

 date various opinions have been held in regard to its structural 

 elements and its essential nature. These opinions have been 

 classified by Schumacher as follows : 



1. The cells of the body are not constituents of the vessel 

 walls, but thread-like accumulations of specific cells, into which 

 bloodvessels penetrate. 



2. The cells are constituents of the bloodvessel walls : 



(a) They are derived from the endothelium. 



(b) They are derived from the. adventitia (" perithelium " 

 cells). 



(c) The cells are related to those of the middle coat of the 

 middle sacral artery and its branches. 



Schumacher has given a full description of the " glomus 

 coccygeum " in the human subject, and the " glomeruli 

 caudales " of other mammals. According to this author, the 

 former corresponds in all essential points to the latter, the only 

 difference being that the " glomeruli caudales " of animals 

 consist of several detached portions corresponding to the 

 caudal segments, while the " glomus " of man is represented 

 by a principal structure at the tip of the coccyx and some 

 smaller nodules. 



It has been shown by Stoerk that the cells of the coccygeal 

 body do not give the chromic reaction at any period of life, 

 and that they bear no histogenetic relation to the sympathetic 

 nervous system. 



The "glomeruli caudales" and the "glomus coccygeum" 

 appear to be arterio-venous anastomoses (Schumacher), and 

 the epithelioid cells are transformations of the smooth muscle 

 fibres of the middle coat of the artery. 



The structures in question are probably to be regarded as 

 safety-valves in the course of the peripheral circulation. The 

 balance of evidence is against their having any kind of internal 

 secretion* 



