574
E T I E N N E W O L F F
He noted that when the brain was orientated in the same direction as
the host-embryo, the differentiation of the latter appeared to be inhibited. When the brain was orientated in the opposite direction the
differentiation of the host-embryo did not seem to be affected. The
author concluded that polarity plays an important role in the phenomenon of specific inhibition.
In a more recent publication, Katoh (1961b) reported his attempts
to fractionate the substance responsible for the inhibition of brain.
After ultracentrifugation, the mitochondrial fraction and the microsomal fraction were almost completely inactive with regard to their
effect on brain. The fraction of soluble proteins, on the contrary,
remained active in 61°/o of cases.
We might note that research done by Lenicque (1959), Clarke and
McCallion (1959), and Braverman (1961), by the method of injections
into the egg, yielded analogous results with regard to the action of
organic extracts.
(d) Action of specific antibodies. Much recent work has been aimed at the
determination, by immunological methods, of the moment at which
specific or common proteins appear in organs in process of development.
Many experiments involving injection of antibodies have been carried
out, particularly on the embryo in ovo. Few such experiments have
been done on the embryo cultivated in vitro.
In this group of experiments is the work of Ebert (1950), undertaken
to verify a hypothesis of Weiss (1947) according to which small doses
of anti-organ sera would have, besides a general inhibiting action on
growth, a slight stimulating action on the homologous organ.
Ebert's main results tend to prove: (1) that the anti-organ sera at
strong concentrations (over 1/80 for the anti-spleen serum and over
1/30 for the anti-brain serum), have a deleterious action on young
blastoderms of the chick at the stages of the primitive streak and cerebral folds; (2) that weaker concentrations (1/30-1/75 for the anti-brain
serum, 1/80-1/200 for the anti-heart and anti-spleen sera) have no
effect on general morphogenesis but appear to inhibit growth; (3) that
intermediate concentrations of anti-organ sera have a relatively specific
effect. At a dilution of 1 /30 for the anti-brain serum the neural tissues
appear to be most affected. At 1/80, anti-heart and anti-spleen sera
particularly affect mesodermal tissues; lateral plates and somites are
strongly inhibited, and this results in the formation of dwarf embryos.
In some of the experiments, the heart of embryos treated with the antiheart serum was very much retarded in its development whereas
pulsations were present with anti-spleen serum.
These experiments suggest that anti-organ sera can exert an inhibiting action on the homologous organ of blastoderms cultivated in vitro.
E T I E N N E W O L F F
He noted that when the brain was orientated in the same direction as
the host-embryo, the differentiation of the latter appeared to be inhibited. When the brain was orientated in the opposite direction the
differentiation of the host-embryo did not seem to be affected. The
author concluded that polarity plays an important role in the phenomenon of specific inhibition.
In a more recent publication, Katoh (1961b) reported his attempts
to fractionate the substance responsible for the inhibition of brain.
After ultracentrifugation, the mitochondrial fraction and the microsomal fraction were almost completely inactive with regard to their
effect on brain. The fraction of soluble proteins, on the contrary,
remained active in 61°/o of cases.
We might note that research done by Lenicque (1959), Clarke and
McCallion (1959), and Braverman (1961), by the method of injections
into the egg, yielded analogous results with regard to the action of
organic extracts.
(d) Action of specific antibodies. Much recent work has been aimed at the
determination, by immunological methods, of the moment at which
specific or common proteins appear in organs in process of development.
Many experiments involving injection of antibodies have been carried
out, particularly on the embryo in ovo. Few such experiments have
been done on the embryo cultivated in vitro.
In this group of experiments is the work of Ebert (1950), undertaken
to verify a hypothesis of Weiss (1947) according to which small doses
of anti-organ sera would have, besides a general inhibiting action on
growth, a slight stimulating action on the homologous organ.
Ebert's main results tend to prove: (1) that the anti-organ sera at
strong concentrations (over 1/80 for the anti-spleen serum and over
1/30 for the anti-brain serum), have a deleterious action on young
blastoderms of the chick at the stages of the primitive streak and cerebral folds; (2) that weaker concentrations (1/30-1/75 for the anti-brain
serum, 1/80-1/200 for the anti-heart and anti-spleen sera) have no
effect on general morphogenesis but appear to inhibit growth; (3) that
intermediate concentrations of anti-organ sera have a relatively specific
effect. At a dilution of 1 /30 for the anti-brain serum the neural tissues
appear to be most affected. At 1/80, anti-heart and anti-spleen sera
particularly affect mesodermal tissues; lateral plates and somites are
strongly inhibited, and this results in the formation of dwarf embryos.
In some of the experiments, the heart of embryos treated with the antiheart serum was very much retarded in its development whereas
pulsations were present with anti-spleen serum.
These experiments suggest that anti-organ sera can exert an inhibiting action on the homologous organ of blastoderms cultivated in vitro.