1980 Volume 32 Issue 2 Pages 151-187
As already described, potency is tremendous and its developmental change is delicate which is caused by direct or indirect relationships of chemical substances inside the embryo and in between the areas. In order to confirm the relationships, the inductive action in the normal development of the crystalline lens was observed by using the tadopole of the larva bulgaris japonica.
The following conclusions we re obtained.
1) The retina in amphibian is formed by the sustentacular cells and fibers of Willer, migration in the deep layer of the epithelial cells, and the expansion of the protoplast. The origin of glial tissues, excluding the sustentacular cells and fibers, could not be elucidated in our specimen. These glial tissues, however, appear t o be epithelial-cells derivatives, as Bonnet and Peter explained.
2) The lens is induced from the sense layer, or the outer surface in the deep layer, with the radial sustentacular fibers of Muller as its inductor, and with m elanin granules as its induction factor. This fact is also the case with the regenerat ion of the crystalline lens.
3) According to O. Hertwiz, the external limiting membrane of the retina is formed by secretion. We, however, maintain that this specific membrane is a part of the protoplast remaining of the visual-cavity surface of the epithelial cells, or thin bla ck plates.
4) Melanin granules always attach to the surface of the radial sustentacular cells and fibers of Mfillar and are given to the mother tissues by the entering of the fibers.
5) Melanin appears to develop in the form of yolk granules. We, however, were unsuccessful in proving that this pigment granule, melanin, develops from melanoblast.
6) In amphibian, the optic vesicles commence to develop first at the 19 th stage of the development, and from the optic vesicles which contacted the outer surface, th e radial sustentacular fibers migrate into the sensory-layer tissues at the 20th and 21 st stages of development. At the 22nd stage, the optic vesicles begin to develop into the optic cup.
7) O. Hertwig maintains that the internal limiting membrane is formed by secretion. Our observation, however, seem to indicate that a part of the sustentacula r fibers remaining on the lateral outer-surface of the eye cup composes, or is responsible for composing, the internal limiting membrane.
8) We were not successful in clarifying the gluey connection of the processes of Müller's fibers and the visual cells between the fiber baskets of Müller's fiber s enveloping the basement layers of rods and cones and the cubic or short colu mnar cells in the yellow-coloring epithlium layers, as mentioned by W. Kolmer (1936).
9) J. Mann, W. Kolmer et al. report that in vertebrate species and the human fetus the ganglion cell layers in the innermost cell layers of the retina appear first, and O. Hertwig reports that the layer of rods and cones appears last. In our amphibi an tadopole, the pigmented layer of the retina was formed first (2nd 5th stage of development), and the inner plexiform layer, the nuclear layer, and the ganglion ce ll layer appeared respectively (26th stage), and the nerve fiber layer became distingu ishable (27th and 28 th stage). The outer plexiform layer and Henle's fibe r layer, however, did not yet appear as late as at the 31st stage. We, therefore, coul d not distinguish the outer nuclear layer from the inner one.
10) The development of the crystalline lens varies from animal to animal, as many researchers have pointed out. In amphibian, the lens is formed from the sense layer of the outer surface in the deep layer in contact with the optic vesicle, by the induction of the sustentacular fibers of the optic vesicle.
