244
CHARLES S. THORNTON
limb stump is reported to be negative to the proximal stump (Becker,
1961), Rose postulates that positively charged particles (regionally
specific histones?) move from the old tissues to the regenerate in a
"polarized control arc." The movement of informational particles is
visualized as going distally from stump skin to apical wound epithelium
and then proximally to internal blastemal cells. It should be pointed
out, however, that in the axolotl no potential differences can be found
between various levels of the limb (Shuraleff, unpublished). The demonstration by Yntema (1959a) that aneurogenic limbs can regenerate is an
apparent exception to the rule that nerves convey morphogenetic information. Rose, however, points out that embryonic limb bud development
proceeds without nerves and that it is possible that as nerves grow into
limbs they take over a function that was performed in their absence by
the tissues (epidermis?) of the developing limb.
These ideas are highly speculative, but valuable nevertheless for the
stimulus they are providing for the design of new analyses of regenerating
systems. Of primary importance now is the application of the methods of
biochemistry and microbiology to the problems of regeneration (see also
Deuchar, 1966). This is a particularly inviting avenue of investigation,
not only because fundamental processes of development are operative in
regenerating systems, but also because the amount of material in a limb
regenerate, such as that of the axolotl, is considerable—a factor which
should appeal to the biochemist. Furthermore, it is possible to separate
the epidermal and mesodermal components throughout limb regeneration
and analyze the enzymic, nucleic acid, and protein changes which occur
in them. The chemical nature of nerve and hormone influences on regeneration is also little understood. The prospect for the future is a
challenging one, and modern methods of analysis should continue to
make the investigation of regeneration an exciting field indeed.
References
Adova, A. N., and Feldt, A. M. (1939). Compt. Rend. Acad. Sci. URSC 25, 43.
Anton, H. J. (1965). In "Regeneration in Animals" (V. Kiortsis and H. A. L.
Trampusch, eds.), North-Holland Publ., Amsterdam.
Becker, R. 0. (1961). J. Bone Joint Surg. 43A, 643.
Berman, R., Bern, H. A., Nicoll, C. S., and Strohman, R. C. (1964). /. Exptl. Zool.
156, 353.
Bischler, V. (1926). Rev. Suisse Zool. 33, 431.
Blacher, S. L. (1952). Bull. Exptl. Biol. Med. 50.
Bodemer, C. W. (1960). J. Morphol 107, 47.
Bodemer, C. W. (1962a). Anat. Record 142, 457.
Bodemer, C. W. (1962b). Anat. Record 142, 105.
CHARLES S. THORNTON
limb stump is reported to be negative to the proximal stump (Becker,
1961), Rose postulates that positively charged particles (regionally
specific histones?) move from the old tissues to the regenerate in a
"polarized control arc." The movement of informational particles is
visualized as going distally from stump skin to apical wound epithelium
and then proximally to internal blastemal cells. It should be pointed
out, however, that in the axolotl no potential differences can be found
between various levels of the limb (Shuraleff, unpublished). The demonstration by Yntema (1959a) that aneurogenic limbs can regenerate is an
apparent exception to the rule that nerves convey morphogenetic information. Rose, however, points out that embryonic limb bud development
proceeds without nerves and that it is possible that as nerves grow into
limbs they take over a function that was performed in their absence by
the tissues (epidermis?) of the developing limb.
These ideas are highly speculative, but valuable nevertheless for the
stimulus they are providing for the design of new analyses of regenerating
systems. Of primary importance now is the application of the methods of
biochemistry and microbiology to the problems of regeneration (see also
Deuchar, 1966). This is a particularly inviting avenue of investigation,
not only because fundamental processes of development are operative in
regenerating systems, but also because the amount of material in a limb
regenerate, such as that of the axolotl, is considerable—a factor which
should appeal to the biochemist. Furthermore, it is possible to separate
the epidermal and mesodermal components throughout limb regeneration
and analyze the enzymic, nucleic acid, and protein changes which occur
in them. The chemical nature of nerve and hormone influences on regeneration is also little understood. The prospect for the future is a
challenging one, and modern methods of analysis should continue to
make the investigation of regeneration an exciting field indeed.
References
Adova, A. N., and Feldt, A. M. (1939). Compt. Rend. Acad. Sci. URSC 25, 43.
Anton, H. J. (1965). In "Regeneration in Animals" (V. Kiortsis and H. A. L.
Trampusch, eds.), North-Holland Publ., Amsterdam.
Becker, R. 0. (1961). J. Bone Joint Surg. 43A, 643.
Berman, R., Bern, H. A., Nicoll, C. S., and Strohman, R. C. (1964). /. Exptl. Zool.
156, 353.
Bischler, V. (1926). Rev. Suisse Zool. 33, 431.
Blacher, S. L. (1952). Bull. Exptl. Biol. Med. 50.
Bodemer, C. W. (1960). J. Morphol 107, 47.
Bodemer, C. W. (1962a). Anat. Record 142, 457.
Bodemer, C. W. (1962b). Anat. Record 142, 105.