DIFFERENCE IN INDUCTIVE EFFECT OF LIVER TISSUES WITH AND WITHOUT PERISINUSOIDAL BASEMENT MEMBRANE

Differential inductive capacities among liver tissues of several animals were examined by anticipating the correlation between the capacity and the completness of perisinusoidal basement membrane.
The reacting tissue was competent ectoderm of gastrula of Triturus pyrrhogaster , and the inductive effects of livers on the ectoderm were tested by explantation method. The inductive effect of livers being devoid of the membrane (chick and guinea pig) was neural and the tissues having the dense well-developed membrane (reptiles) produced an assembly of neural and meso-dermal tissues, such as notochord and somite or muscle. The livers with the membrane being of intermediate grade of development ( calf, Triturus and mouse) induce mesodermal tissues, but not frequently, together with neural tissue or alone. The liver tissue was more active in mesodermal induction in proportion to the completeness of the perisinusoidal basement membrane.
On the basis of these data the difference in inductive capacity among liver tissues from different kinds of animals were discussed.     

VEGETALIZATION OF PRESUMPTIVE ECTODERM OF NEWT GASTRULAE IN A TRANSFILTER EXPERIMENT WITH FISH SWIMBLADDER AS THE INDUCTOR

The diffusibility of the vegetalizing factor was examined by a transfilter culture using an ethanol-fixed swimbladder of the crucian carp ( Carassius auratus ) as the inductor and presumptive ectoderm from gastrulae of Cynops pyrrhogaster as the responding tissue. Nucleopore filters, about 12–14 μm thick, with nominal pore sizes of 0.05, 0.1, 0.6, 0.8, 3.0 and 8.0 μm were interposed between the interacting tissues. The responding pieces of ectoderm were removed from the assemblies after contact for 0.5, 1, 3, or 24 hr and cultured in Holtfreter's solution for 10 days at 20°C.
The inductions observed were almost entirely mesodermal, although masses of endoderm-like yolky cells were seen in explants and neural tissues in a few cases. Filter membranes with pores of 0.05 to 8.0 μm did not interfere with the vegetalizing effect.
Under an electron microscope, small cytoplasmic cones of the responding cells of the presumptive ectoderm were observed in the pores of the interposed filter after 3 hr's contact. The cones grew longer as the cultivation time increased, but even after 24 hr there was no contact between the interacting tissues. Since 3 hr's contact between the interacting tissues was sufficient to cause full vegetalization on the transfilter culture with the swimbladder, the formation of the cytoplasmic outgrowths had no significance in the induction.