92
Number of fibers or cells
o
o
o
o
o
o
o
o
o
o
°
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
o
-l
1
1
1
1
1
1
«
1
1
1
1
1
rARTHUR HUGHES
•
Ventral horn cells
o
Ventral roots S 7 -S |0
6 6 r
^6
Length of tail (mm)
-i
1 -
10
I I
12 13
14
Days of development
FIG. 3. Counts in embryos of Eleutherodactylus
at various stages of cells in lumbar ventral horn and of fibers in lumbar ventral roots on one side, from S 7 to S™,
inclusive. (From Hughes, 1965.)
At stage 57, however, a period begins when normal cell death is halted
after amputation. At that time the total number of cells in the normal
ventral horn is still falling. An apparent "pileup" of cells on the amputated side then results as the number there remains stationary, while the
contralateral total continues to decline. Finally, at stages when cell degeneration has ceased within the normal ventral horn, little or no immediate change follows amputation. Many neurons that have suffered
i
i
r -
7
8
9
3y
3
2 I