48
TUNEO
YAMADA
mean a control of the pattern of protein synthesis of a cell group by an
external agent. In this sense, one obvious hypothesis would be that
within the reacting cell the protein synthesizing apparatus is the target
of the inductive influence. Of some interest in this respect is the fact that
most of the macromolecules which have been found effective in causing
specific induction are components of the protein synthesizing apparatus
of the inductor cell. This is clearly the case for the microsome fraction
of the Triturus embryo (Section V), and ribonucleoproteins of guinea-pig
liver and kidney (Section IV). Further, the method of preparation of
the bone marrow factor (Section IV) coincides with that of the amino
acid activating enzyme, although a test of the bone marrow factor for
enzymatic activity has given negative results so far. A relationship of
the inducing agents of differentiated tissue to the protein synthesizing
apparatus is also suggested by the fact that the regional effect of the
tissue on the ectoderm is highly dependent on the nutritive condition of
tissue cells (Toivonen, 1952; Engländerand Johnen, 1957; Vahs, 1957;
Saxén and Toivonen, 1958).
It need not be added that for further elucidation of the mechanism of
the organizer action information is needed concerning the behaviour of
inducing agents after they get into the interior of the reacting cells.
According to Waddington and Mulherkar (1957), and Sirlin and
Brahma (1959) the normal inducing agent may be located in the cytoplasm of the reacting cells. As to the bone marrow factor, Vainio's (1958)
report that it is an efficient antigen, is encouraging. It is hoped that the
localization of the protein within the reacting cell will be possible by the
use of the fluorescent antibody. However, essential understanding of
the organizer action will only be obtained when the first biochemical or
biophysical changes evoked by the inducing agent within the cell are
known. Although in this respect various cell activities enumerated in
Sections III and VIII will be considered, cellular affinity should not be
forgotten. That the change in the pattern of cellular contact is one of the
first manifestations of the action of the organizer on the ectoderm has
been ably discussed by Brown, Hamburger, and Schmitt (1941) and
Schmitt (1941), and experimentally supported by Gillette (1944).
Steinberg (1958) suggested the hypothesis that differential cell affinity
may be based on the highly ordered lattice arrangement of certain
ionized acidic groups on the cell surface. One might then expect that
through the inductive effect, a change occurs in the lattice arrangement
of the cell surface. The recent electron microscopic data strongly suggest
the view that the cell membrane is in dynamic continuity with other
membranous structures of the cell interior including the nuclear membranes (Bennett, 1956; Robertson, 1959). Hence, it is not difficult to
conceive a quick change in the molecular pattern on the cell surface
TUNEO
YAMADA
mean a control of the pattern of protein synthesis of a cell group by an
external agent. In this sense, one obvious hypothesis would be that
within the reacting cell the protein synthesizing apparatus is the target
of the inductive influence. Of some interest in this respect is the fact that
most of the macromolecules which have been found effective in causing
specific induction are components of the protein synthesizing apparatus
of the inductor cell. This is clearly the case for the microsome fraction
of the Triturus embryo (Section V), and ribonucleoproteins of guinea-pig
liver and kidney (Section IV). Further, the method of preparation of
the bone marrow factor (Section IV) coincides with that of the amino
acid activating enzyme, although a test of the bone marrow factor for
enzymatic activity has given negative results so far. A relationship of
the inducing agents of differentiated tissue to the protein synthesizing
apparatus is also suggested by the fact that the regional effect of the
tissue on the ectoderm is highly dependent on the nutritive condition of
tissue cells (Toivonen, 1952; Engländerand Johnen, 1957; Vahs, 1957;
Saxén and Toivonen, 1958).
It need not be added that for further elucidation of the mechanism of
the organizer action information is needed concerning the behaviour of
inducing agents after they get into the interior of the reacting cells.
According to Waddington and Mulherkar (1957), and Sirlin and
Brahma (1959) the normal inducing agent may be located in the cytoplasm of the reacting cells. As to the bone marrow factor, Vainio's (1958)
report that it is an efficient antigen, is encouraging. It is hoped that the
localization of the protein within the reacting cell will be possible by the
use of the fluorescent antibody. However, essential understanding of
the organizer action will only be obtained when the first biochemical or
biophysical changes evoked by the inducing agent within the cell are
known. Although in this respect various cell activities enumerated in
Sections III and VIII will be considered, cellular affinity should not be
forgotten. That the change in the pattern of cellular contact is one of the
first manifestations of the action of the organizer on the ectoderm has
been ably discussed by Brown, Hamburger, and Schmitt (1941) and
Schmitt (1941), and experimentally supported by Gillette (1944).
Steinberg (1958) suggested the hypothesis that differential cell affinity
may be based on the highly ordered lattice arrangement of certain
ionized acidic groups on the cell surface. One might then expect that
through the inductive effect, a change occurs in the lattice arrangement
of the cell surface. The recent electron microscopic data strongly suggest
the view that the cell membrane is in dynamic continuity with other
membranous structures of the cell interior including the nuclear membranes (Bennett, 1956; Robertson, 1959). Hence, it is not difficult to
conceive a quick change in the molecular pattern on the cell surface