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Cruce 
Figure 6. Photomicrographs of degeneration in the 8th segment (midbrachial) of the lizard spinal cord fol- 
lowing a complete hemisection of the first spinal segment. The same section as pictured in Figure 5. (D) 
Low power photo of the spinal gray matter with the ipsilateral side on the left: squares indicate where 
high-power photos were taken. (A) The dorsal gray commissure (lamina X) : Note that it is filled with 
degenerating axons-of-passage (arrows). (B) The ventral white commissure: Note the bundles of degen- 
erating axons-of-passage (arrows). (C) The lateral border of ipsilateral lamina VII with the white matter: 
Note degenerating axons-of-passage (arrows) entering from the upper left and passing toward more 
medial regions; slight evidence of preterminal and terminal debris can also be seen (open arrow). (F) The 
lateral border of contralateral lamina VII with the white matter: Note the absence of axonal debris and con- 
trast this with the ipsilateral region seen in (C). (D) Ipsilateral lamina VII: Note that it is filled with 
a large amount of preterminal and terminal debris as well as axons-of-passage (arrows) which are coursing 
into the ventral commissure. (G) Contralateral laminae VIII and medial IX: Note that the region is filled 
with preterminal and terminal debris and compare this with the ipsilateral region seen in Figure 5F. Ab- 
breviations are: central canal (CC), lateral column (LC), and medial longitudinal fasciculus (MLF). Re- 
produced from Cruce (1975), Brain, Behavior, and Evolution, with permission of the publisher. 
