[Click plate for enlarged versions of pictures.]
Figure 1 is a cross section through the distal end of a normally
regenerated forearm (antibrachium) 6 weeks after amputation. The arrow points
to the ulnocarpalis muscle. Small but constant, the latter muscle is an
excellent landmark in a cross section through most of the forearm and wrist.
It is part of an interior stratum of muscles, runs ventral and
parallel to the ulna in the forearm and the ulnare carpal in the wrist and inserts into carpale III (in the distral row of carpals).
Figure 2 is through the wrist of a regenerated transplant; the arrow
points to a normal-appearing extensor digitorum muscle; but on the ventral side
of the
carpals (lower part of the picture) the organization is completely atypical of
the muscular pattern in the wrist (see normal wrist pattern
here).
Figure 3, which is at the same level as the control in
figure 1, shows a cylindrical, unfasciculated mass of skeletal muscle tissue.
The same is true of Figure 4, except that the level is mid-antibrachium
(compare with Fig. 1). Figure 5 shows a partially normal pattern (like
2) and is placed here for comparison with Figure 6 which is through
the
mid-wrist. The latter completely lacks organization typical of virtually any
normal vertebrate forelimb. Compare with the patterns at this
location.That the profound changes in muscle pattern were in fact related to spinal cord was evident in experiments in which the tissues were stained for nerve fibers.
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