Chapter XXII 



RECONSTRUCTION OF THE GRA^ MATTER IN THE 

 BRAIN STEM OF TROGLOD\TES GORILLA 



The High Cer\ical Level of the Spinal Cord 



"^H Ii upper Ic'Nc'l ol tlu' ciTNical (.'ord presents an appearance strik- 

 intil\ sniiilar to that totiiul ni tlie hiiih cervical le\'el ol the human 

 spuial cord. In the le\el at which th(.' reconstruction ls l)cgun, the 

 \entral gray columns are still in contact with the central gray matter of the 

 cord. Lateral to the \entral gra\ column is the small lateral cell column 

 behind w hicii is an ari'a alread\' showing indications ol reticular lormation. 

 The ventral gra\' column is hert' roughly triangular in outline, with its apex 

 directed ventrally. It i^resents a mesial surlact' which is more or less parallel 

 w ith the fellow ot" the opjiosite side, a lateral sloping surface and a base w liich 

 is in contact w ith the central gra\' matter. 



The cer\'i\ and base of tlu' dorsal gray column are both directed ven- 

 trodorsally, while the substantia gelatinosa Rolandi which surmounts the 

 dorsal horn and Hares somewhat latcrall\ presents a typical |)rimate 

 appearanct-. As the junction ot the high eer\ical le\'el with the oblongata 

 is ap|)roached, the \entral gra\- column diminishes in size and linally merges 

 with the reticular lormation which has incrcasi'd in size pari passu with the 

 decrease in the \entral gray column. 



The substantia gelatinosa Rolandi as it appears to merge with tlu' 

 substantia gelatinosa trigemini graduall\ assumes the more lateral j^osition 

 characteristic of it in the oblongata. 



The reticular lormation graduall\ increases m size in the oblongata and 



spreading laterally establishes contact w ith the ventromesial surface of the 



substantia gelatinosa trigemini. It eventually replaces the ventral gray 



685 



