Über die einleitenden Vorgänge bei der ersten Entstehung der Nervenfasern im Nervus opticus

Szily, A. v.

doi:10.1007/bf01858221

Cited by 28 publications

(5 citation statements)

References 5 publications

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“…In this mutant strain, the volume of the extracellular channels becomes increasingly diminished and during the usual stage of formation of the optic nerve, the retinal ganglion cell axons repeatedly fail to exit from the globe (Silver and Robb,'79). At present, our results do not suggest that long columns of cells degenerate and, thus, leave pathways of chemically filled spaces in their wake, as was first suggested by Von Szily (1912). In fact, large openings appear in portions of the retina that never become necrotic (i.e., peripherally).…”

Section: Discussioncontrasting

confidence: 53%

A mechanism for the guidance and topographic patterning of retinal ganglion cell axons

Silver

Sidman

1980

J of Comparative Neurology

317

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Three dimensional reconstruction, with the use of serial, 1-micrometer sections, has revealed a system of oriented intercellular spaces within the undifferentiated optic cup. These large openings appear in the marginal zone of the primitive retina and optic stalk prior to the formation of the first retinal ganglion cell axons. The spaces at the region of the optic disc form sets of long, interconnecting tunnels oriented in the direction of the stalk. The spaces at the back and rim of the cup form blind, radially arranged pockets. The extracellular tunnels of the optic disc region strictly maintain their positions in relation to the optic fissure and, thus, discrete portions of the retina become connected by continuous openings with equivalent regions in the stalk. The path taken by the earliest outgrowing optic fibers is identical to the one previously established by the intercellular tunnels. We propose that the tunnel and pocket layout may provide directional and topographic information to the first forming optic axons.

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Section: Discussioncontrasting

confidence: 53%

A mechanism for the guidance and topographic patterning of retinal ganglion cell axons

Silver

Sidman

1980

J of Comparative Neurology

317

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“…Von Szily (1912) was the first to point out that axons can use the channels opened up by degenerating cells. Before the formation of pioneer optic axons, Silver and Sidman (1980) and Horsburgh and Sefton (1986), in their studies of the rodent retina, demonstrated the existence of extracellular spaces that apparently form channels arranged in the direction of the optic stalk.…”

Section: Discussionmentioning

confidence: 99%

“…The possible role of cell degeneration in the posterior pole of the neural retina during the emergence of the first optic fiber fascicles may be the creation of extracellular spaces through which the optic fibers are able to leave the retina. Von Szily (1912) was the first to point out that axons can use the channels opened up by degenerating cells. Before the formation of pioneer optic axons, Silver and Sidman (1980) and Horsburgh and Sefton (1986), in their studies of the rodent retina, demonstrated the existence of extracellular spaces that apparently form channels arranged in the direction of the optic stalk.…”

Section: Discussionmentioning

confidence: 99%

Cell death in the ventral region of the neural retina during the early development of the chick embryo eye

et al. 1988

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The present study deals with morphologic and quantitative changes that take place in the area of cell death in the ventral part of the presumptive retinal wall of the chick embryo. These changes were followed from the optic vesicle stage until the first optic fiber fascicles leave the neural retina. Our results show that both the volume occupied by the area of cell death and the density of its pyknotic fragments undergo considerable variation during the period between Hamburger and Hamilton's (1951) stages 12 to 20. In the optic vesicle stages, cell death in the ventral wall of the vesicle was observed in 50 to 75% of the embryos studied. During stages 14 and 15, this zone was seen in more than 90%. By the time invagination of the optic cup was complete, the ventral retinal zone of cell death had disappeared entirely in a large proportion of embryos; in all others, it shrank significantly both in volume and density of pyknotic fragments. In stage 19, when the first optic fiber fascicles begin to emerge from the retina, a dramatic increase occurs in the number of pyknotic fragments in the posterior pole of the retina. The appearance of dying cells, in a region shortly to be traversed by developing ganglion cell axons, supports the hypothesis that cell death processes are apparently somehow related to the creation of a suitable environment for the emergence of fibers toward the optic stalk. Densities of mitotic and interphasic cells as well as the mitotic index were determined in both the retinal zone of cell death and in areas devoid of dead cells. In all developmental stages analyzed, the mitotic index was notably lower in the former than in non-necrotic zones, suggesting that cell proliferation is partially inhibited in retinal areas of cell death.

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“…There is overwhelming experimental evidence that degenerating cells in the process of chromatopycnosis and chromatolysis are resorbed b; cells which may subsequently divide (Spear & Glucksmann, 1937; Dustin, 1947)~ and no evidence to show that these 'mitotic metabolites' are derived from chromatic material of a normally dividing cell. The proof that the described degenerative processes lead to the death of the cell rests on the analysis of transitional stages up to final cytolysis in normal material (Glucksmann,193oa), in material exposed to radiation injury (Glucksmann & Tansley, 1936;Spear and Glucksmann, 1937), and on the identity of these processes with those observed under pathological conditions (v. Szily, 1912;Froboese, 1926;Ernst, 1926Ernst, , 1929 (Dustin, 1947). In such experiments the appearance of the various stages can be clearly identified up to the complete resorption of the dead cells, and the sequence of stages can thus be clearly established.…”

Section: The Morphology Of Cell Death During Normal Vertebrate Develomentioning

confidence: 99%

Cell Deaths in Normal Vertebrate Ontogeny

1951

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Summary i. Degenerations of embryonic cells have either been reported as such or have been misinterpreted by various authors as ‘mitotic metabolites’ or blood cells. 2. There is ample support for the morphological identification of dying cells from the following considerations: the degeneration ‘granules’ are initially Feulgen‐positive and have thus originated from nuclear constituents; the stages of cell deaths seen in normal embryos are identical with those produced experimentally and with those observed directly in tissue cultures; degenerating cells react in the same manner to supravital stains in vivo and in vitro. 3. The process of degeneration varies with the degree of specialization of the cell, with its functional state (e.g. mitosis), with the type of animal and under experimental conditions with the causative agents. 4. Cell death may take from less than 1 hr. to about 7 hr. when only a small proportion of a living tissue dies, but may be prolonged to days when numerous cells die simultaneously and their resorption is delayed. 5. Degenerations have been found during the normal development in embryos of all vertebrate animals examined. The occurrence of necrosis in embryos of pure genetical lines is excluded from this article. 6. The incidence of embryonic cell deaths according to site, tissue, developmental stage or process and type of animal is summarized in Table 1. 7. While some degenerations have no obvious function in embryonic development, others seem to play a significant role in embryonic processes, e.g. the morphogenesis and histogenesis of tissues and organs, and the representation and regression of phylogenetic steps (Table 2). 8. Morphogenetic degenerations precede changes in the form of epithelial organs, e.g. during the invagination of the optic cup, the formation of the crystalline lens, the olfactory pit, the neural tube, etc. They bring about the separation of rudiments such as that of the neural tube and the lens from the ectoderm. They reduce the excessive thickening of uniting edges such as those of the body wall and of the mandibles. They are involved in the production of lumina in the solid rudiments of glands and the intestinal tract. In the mesenchyme they precede and make possible the influx of specialized tissue such as the sternal plates or the ingrowth of myogenic tissue in the mandible. 9. Histiogenetic degenerations are related to the differentiation of tissues and organs. The differentiation of the three cell layers of the frog tadpole retina, for instance, is accompanied by three waves of degeneration. Similar cell deaths of early neuroblasts are found in the spinal ganglia outside the limb regions. In amphibia a partial sarcolysis during metamorphosis provides a blastema for the permanent musculature. Sex differentiation of the individual involves the partial degeneration of the Mullerian or Wolffian ducts. Cell deaths also occur in relation to fibre formation and to the appearance of bone and cartilage matrix. Their role in these and in evocatory processes needs furthe...

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Über die einleitenden Vorgänge bei der ersten Entstehung der Nervenfasern im Nervus opticus

Cited by 28 publications

References 5 publications

A mechanism for the guidance and topographic patterning of retinal ganglion cell axons

A mechanism for the guidance and topographic patterning of retinal ganglion cell axons

Cell death in the ventral region of the neural retina during the early development of the chick embryo eye

Cell Deaths in Normal Vertebrate Ontogeny

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