7o 
MAMMALIAN ANATOMY 
fila radicularia of the nerves, and determine their relation to 
the gray nerve substance. 
Commissural Fibers. —Note that these lie either within the 
gray substance of the cross bar of the H (gray commissure), or 
ventral to the gray substance (white commissure). Determine 
so far as possible the connections which these make. 
The Longitudinal Bundles of Fibers (Fasciculi). —Note that 
these make up the bulk of the white funiculi, and are here cut 
transversely. Note, under high power, that these fibers are 
medullated. while the neurilemma is absent and a sheath of areolar 
* 
tissue takes its place. Compare with fibers seen in sections of 
nerve roots outside of the cord. 
Nerve Roots and Ganglion. —The general course of the dorsal 
root bundles of medullated fibers into and through the ganglion, 
between the groups of perikarya of sensory neurons. Why do the 
sections of the latter have rounded outlines? Are any of these cut 
through a process? Note the sheath of supporting cells around 
each perikaryon. Note the relation of the ventral root bundles to 
the ganglion. 
Select one good characteristic section , passing through a ganglion 
if possible , make of it as large an outline drawing as your page allows , 
to show the general topography as seen under the low power , and dll 
in in their proper regions the details of perikarya and fibers as studied 
under the high power . 
