77//'.' iiSK srurcrriiE of riiK I'R(h; v.\ 



curiuTS ol (he liapc/iiitl of ^ray matter cxtciid tlursad and vni- 

 trad, forming the so-called dorsul and vt nlral Imrns of gray matter 

 The larger cell bodies seen in the ventral horns are those of the 

 inolor cells whose axones extend out to the voluntary muscles or 

 other effectors of the body following ii course through the ventral 

 root of a spinal nerve. I'^xamine one of these under high jjower. 

 The structure of the cell l)ody is well shown hut only the begin- 

 nings of the processes are present, as these have been cut across in 

 preparing the thin sections. Note the relatively large iiurleus 

 of the cell body containing a conspicuous round body, the 

 nucleolus. Often a more deeply staining group of cells may be 

 seen in the center of the cross-section, the epithelial cells lining 

 the cavity of the cord. 



The general structure of nervous tissue may be determined 

 by the study of j^repared slides of teased and stained tissue. 



Sketch a cross-section of the cord as it appears under low 

 power (about two and one-half inches in diameter), stippling the 

 grey matter more heavily than the white matter. Do not attempt 

 to show cellular structure in the cross-section but draw a single 

 motor cell body separately as seen under high power. 



