18
TUNEO
YAMADA
Pioneering in this direction Toivonen and his collaborator Kussi
attempted to characterize the substance responsible for the archencephalic effect produced by guinea-pig liver and that responsible for the
spino-caudal or deuterencephalic effect produced by guinea-pig kidney.
In an earlier paper Toivonen (1950) concluded that the archencephalic
factor is relatively thermostable, soluble in petroleum ether, accomTABLE I
Regional Induction caused by Heterogenous Inductors
Regional Types
Main Structures
Examples of Inductors
Archencephalic ^)
Acrogenetic^
Fore-brain
Eye
Nose
Lens
Guinea-pig liver (Toivonen, 1940)
Outer layer of mouse kidney
cortex (Mifune, 1955)
Deuterencephalic <
3)
Deutogenetic^
Mid-brain
Hind-brain
Ear vesicle
Guinea-pig kidney (Toivonen, 1940)
Liver of Uroloncha domestica (Hama,
1944)
Spino-caudal
( 5 )
Tritogenetic^
Spinal cord
Tail notochord
Tail somites
Guinea-pig kidney (Toivonen, 1940)
Newt liver (Chuang, 1939)
Trunk-mesodermal
Trunk notochord
Trunk somites
Nephric tubules
Mesothelium
Blood island
Guinea-pig bone marrow (Toivonen,
1953)
Frogskin (Fujii, 1941)
Endodermal
Pharynx
Stomach
Intestine
Guinea-pig bone marrow (Yamada,
1958c)
(1), (3), and (5) after Lehmann (1945).
(2), (4), and (6) after Dalcq (1957b).
panies the nucleoproteins in fractionation, endures ethanol treatment
and is readily dialyzable, while the spino-caudal factor is thermolabile,
not extractable with petroleum ether, non-dialyzable, and is inactivated
by formalin and proteolytic enzymes. The results of Kuusi's (1951)
extensive experiments testing subcellular components, nucleohistone
samples, saline extracts, tissues treated with formalin, and homogenates
treated with ribonuclease are difficult to summarize briefly. Her own
conclusion drawn from these experiments was that the archencephalic