32
T U N E O
Y A M A D A
F I G . 1 2 . A n ear vesicle formed in isolated Triturus ectoderm cultured in a suspension
of the microsome fraction of Triturus neurulae. χ 90.
b). The frequency of induction roughly parallels the RNA content of the
sample. Tobacco mosaic virus treated with ethanol also shows a high
inducing ability. Ribonuclease treatment of the liver pellet and of
tobacco mosaic virus almost completely suppresses their inductive
activity, (iii) The pattern of distribution of RNA within an amphibian
embryo, which is demonstrable with basophilic stains, follows the well
known gradient along the animal-vegetal, and dorso-ventral axis. The
temporal change of the pattern in the course of gastrulation and
neurulation provides a basis for the argument that the R N A enriched
in the organizer area is transferred to the ectoderm with which it comes
in contact during invagination.
amphibian gastrulae, a positive correlation is found between the loss of
cytoplasmic basophilia of the implant and the occurrence of induction
(Brächet, 1942). Further an enhancement of RNA synthesis as judged
by cytoplasmic basophilia occurs in the host ectoderm which is in
contact with the implant and is induced to neural differentiation,
(ii) Implantation into the blastocoel of ethanol-treated, RNA-rich
pellets prepared by ultracentrifugation from amphibian gastrulae, liver,
kidney, and yeast is followed by neural induction (Brächet, 1943,1947a,
T U N E O
Y A M A D A
F I G . 1 2 . A n ear vesicle formed in isolated Triturus ectoderm cultured in a suspension
of the microsome fraction of Triturus neurulae. χ 90.
b). The frequency of induction roughly parallels the RNA content of the
sample. Tobacco mosaic virus treated with ethanol also shows a high
inducing ability. Ribonuclease treatment of the liver pellet and of
tobacco mosaic virus almost completely suppresses their inductive
activity, (iii) The pattern of distribution of RNA within an amphibian
embryo, which is demonstrable with basophilic stains, follows the well
known gradient along the animal-vegetal, and dorso-ventral axis. The
temporal change of the pattern in the course of gastrulation and
neurulation provides a basis for the argument that the R N A enriched
in the organizer area is transferred to the ectoderm with which it comes
in contact during invagination.
amphibian gastrulae, a positive correlation is found between the loss of
cytoplasmic basophilia of the implant and the occurrence of induction
(Brächet, 1942). Further an enhancement of RNA synthesis as judged
by cytoplasmic basophilia occurs in the host ectoderm which is in
contact with the implant and is induced to neural differentiation,
(ii) Implantation into the blastocoel of ethanol-treated, RNA-rich
pellets prepared by ultracentrifugation from amphibian gastrulae, liver,
kidney, and yeast is followed by neural induction (Brächet, 1943,1947a,