96
ARTHUR HUGHES
120
80 H
3 DAYS AFTER
AMPUTATION AT
KNEE AT 10 DAYS
PHASE in
CELL NUMBERS/10 SECTIONS
3 DAYS AFTER
AMPUTATION AT
HIP AT 10 DAYS
PHASE n
A
10 20 30 40 50 60 70 80 P A A
10 20 30 40 50 60 70
SERIAL TRANSVERSE SECTIONS THROUGH VENTRAL HORNS
FIG. 6. Number of cells in lumbar ventral horns of embryos of
Eleutherodactylus
3 days after amputation at knee (left) and at hip (right). The operation was performed at 10 days. The data are again given for serial groups of five sections
through the ventral horns, with the anterior pole to left of figures. More cells are
found ipsilaterally in both knee- and hip-amputated embryos, since ventral horn
cells innervating all regions of the limb have now entered Phase III.
ventral horn innervate the limb at proximal levels, mainly the flexor
muscles of the hip joint, is given by the results of stimulating the lumbar
nerves in turn (described below).
D. Innervation of the Limb at Functional Stages
Evidence from studies on the amputation of developing limbs shows
that the differentiation of the ventral horn is controlled by the periphery.
Craniocaudal maturation of the ventral horn is geared to proximodistal
development of the limb. On this basis a hypothesis may be advanced
that successive generations of new axons entering the limb plexus come
from definite levels of the ventral horn and establish contact with de-