30
TUNEO
YAMADA
is probably devoid of inducing activity. If we assume that microsomes
are alone responsible for regional induction of living embryonic areas,
the sample of microsomes used in the present experiment must be
heterogenous as to regionality, since it contains microsomes of the
whole neurula, which is composed of areas having all types of regional
inductive effects, as evidenced by insertion experiments of Mangold
(1933), transplantation experiments of Holtfreter (1933a), and explanaTABLE IV
Inductive Effects of Some of the Subcellular Fractions of Triturus Embryos
Tested on Isolated Ectoderm with the Nylon Technique
Fractions
Protein
Concentration
Archencephalic
• Deuteren' cephalic
Spinocaudal
Mesodermal
Indiffer.
Neural
No
Induction
Microsomes
(nylon)
300 /xg/ml
18/35
6/35
2/35
4/35
7/35
6/35
Microsomes
(nylon)
200 /ig/ml
7/12
0/12
0/12
0/12
0/12
4/12
Acid Precipitable
(nylon)
200 ¿tg/ml
0/9
0/9
0/9
0/9
0/9'
9/9
Acid Precipitable
(nylon-less)
200 /ig/ml
0/6
0/6
0/6
0/6
0/6
6/6
Acid Soluble
(nylon)
300 μg|m[
9/35
0/35
0/35
0/35
2/35
24/35
The frequency of induction is indicated by the number of explants containing induced
structures of the given type divided by the total number of explants of the series.
tion experiments of Ter Horst (1948). Thus, one might expect that the
whole series of regional types are induced by the microsome fraction.
The expectation is fulfilled in so far as all types of regionality are observed
in the series (Table IV), but the predominant appearance of archencephalic induction requires special consideration. One possible interpretation is that during the process of isolation or testing, the inductive
effect of microsomes, which originally belonged to types other than the
archencephalic type, is converted into the archencephalic type. Such
conversion of the regional type is well known in heterogenous inductors,
and occurs very extensively in the case of the ribonucleoproteins of
guinea-pig liver and kidney, which are probably of microsomal origin.
As another possible explanation of the predominance of archencephalic
TUNEO
YAMADA
is probably devoid of inducing activity. If we assume that microsomes
are alone responsible for regional induction of living embryonic areas,
the sample of microsomes used in the present experiment must be
heterogenous as to regionality, since it contains microsomes of the
whole neurula, which is composed of areas having all types of regional
inductive effects, as evidenced by insertion experiments of Mangold
(1933), transplantation experiments of Holtfreter (1933a), and explanaTABLE IV
Inductive Effects of Some of the Subcellular Fractions of Triturus Embryos
Tested on Isolated Ectoderm with the Nylon Technique
Fractions
Protein
Concentration
Archencephalic
• Deuteren' cephalic
Spinocaudal
Mesodermal
Indiffer.
Neural
No
Induction
Microsomes
(nylon)
300 /xg/ml
18/35
6/35
2/35
4/35
7/35
6/35
Microsomes
(nylon)
200 /ig/ml
7/12
0/12
0/12
0/12
0/12
4/12
Acid Precipitable
(nylon)
200 ¿tg/ml
0/9
0/9
0/9
0/9
0/9'
9/9
Acid Precipitable
(nylon-less)
200 /ig/ml
0/6
0/6
0/6
0/6
0/6
6/6
Acid Soluble
(nylon)
300 μg|m[
9/35
0/35
0/35
0/35
2/35
24/35
The frequency of induction is indicated by the number of explants containing induced
structures of the given type divided by the total number of explants of the series.
tion experiments of Ter Horst (1948). Thus, one might expect that the
whole series of regional types are induced by the microsome fraction.
The expectation is fulfilled in so far as all types of regionality are observed
in the series (Table IV), but the predominant appearance of archencephalic induction requires special consideration. One possible interpretation is that during the process of isolation or testing, the inductive
effect of microsomes, which originally belonged to types other than the
archencephalic type, is converted into the archencephalic type. Such
conversion of the regional type is well known in heterogenous inductors,
and occurs very extensively in the case of the ribonucleoproteins of
guinea-pig liver and kidney, which are probably of microsomal origin.
As another possible explanation of the predominance of archencephalic