224 



THE ESSENTIALS OF HISTOLOGY. 



The central canal of the spinal cord is lined by columnar ciliated 

 epithelium-cells, which are surrounded by a quantity of neuroglia. 

 The cells are best seen in the spinal cord of animals and in the child 

 (fig. 255) ; in the human adult they have frequently become proliferated, 

 and their cilia are no longer visible. 



FIG. 254. FROM A LONGITUDINAL SEC- 

 TION OF SPINAL COED, SHOWING THE 

 ENTRANCE OF POSTERIOR ROOT-FIBRES. 



(Earn on y Cajal. ) 



A, A, fibres entering the postero-lateral 

 column, and bifurcating into an ascending 

 and descending division ; B, C, collaterals 

 passing from them into the grey matter ; 

 E, other fibres of the posterior white 

 columns also giving off collaterals. 



FIG. 255. A, SECTION OF THE CENTRAL 



CANAL OF THE SPINAL CORD OF A CHILD, 

 SHOWING ITS CILIATED EPITHELIUM 

 AND THE SURROUNDING CENTRAL NEU- 

 ROGLIA. (Moderately magnified.) B, 

 SOME OF THE CILIATED CELLS. (Highly 



magnified.) 



Characters of the spinal cord in the several regions (figs. 252, 256). 

 In the cervical region the white matter, especially that of the lateral 

 columns, occurs in largest proportion. The grey matter, especially in 

 the cervical enlargement, is in considerable amount (C 5), and it en- 

 croaches in the form of a network upon the adjacent part of the lateral 



