File:The American journal of anatomy (1901) (14597390259).jpg

Identifier: americanjournalo06wist (find matches)
Title: The American journal of anatomy
Year: 1901 (1900s)
Authors: Wistar Institute of Anatomy and Biology Association of American Anatomists
Subjects: Anatomy Anatomy
Publisher: Baltimore, MD : (s.n.)
Contributing Library: MBLWHOI Library
Digitizing Sponsor: MBLWHOI Library

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ion of the optic vesicle into the region between the otic capsuleand medulla. Section through transplanted eye, otic capsule, and medulla.The eye, owing to irregular invagination, has only a very narrow pupil andsmall, irregular cup cavity. Most of the optic nerve-fibers pass from theirregular ganglionic layer through the narrow pupil into the mesenchymeventral to the otic capsule, where it splits into two divisions, the ventralone of these runs a short distance and ends abruptly in the mesenchyme,the other runs to the cartilage ventral to the otic vesicle and can be tracedfor a short distance along it. The peripheral portion of the nerve, as shownin the figure, is projected into the section from the neighboring sections.Another portion of the optic nerve, smaller than the first one, runs throughthe retina and seems to end abruptly at the pigment layer. This portion ofthe nerve has also been projected into the figure from a neighboring sec-tion. X 90 diameters. Warren Harmon Lewis 471
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EXPEKIMENTAL STUDIES ON THE DEVELOPMENT OF THE EYE IN AMPHIBIA. III. ON THE ORIGIN AND DIFFERENTIATION OF THE LENS. WARREN HARMON LEWIS. Associate Professor of Anatomy, Johns Hopkins University. With 83 Figures. Introduction-.Since the publication of my paper on the origin of the lens in ranapalustris/ I have made many new experiments on lens-formation withregenerating and transplanted eyes, not only in rana palustris but in ranasylvatica and amblystoma punctatum. My pupil, Mr. Le Cron, hasalso made experiments in the same field on amblystoma.* These newexperiments confirm the conclusions given in my previous paper forrana palustris and throw additional light on the origin and early de-velopment of the lens. They leave no doubt, I believe, but that a lens,arising from the ectoderm in the amphibian embryo, is dependent forits origin on the contact influence of the optic vesicle on the ectoderm,in other words, the lens is not a self-originating structure. Theseexperiments indicate that

Fig. 14. Experiment DF₇. Embryo rana palustris killed 4 days after transplantation of optic vesicle into position caudal to normal eye region. Section through transplanted eye showing formation of optic cup and course of optic nerve from transplanted eye into medulla in the region of the V nerve. The optic nerve passes through the marginal veil into the grey matter where the fibers become scattered and can only be followed for a few sections anteriorly. The transplanted eye is separated from the ectoderm by mesenchyme and is without a lens. It is in contact with the medulla. x 90 diameters.

Fig. 15. Experiment DF₁₇. Embryo of rana palustris killed 5 days after transplantation of the optic vesicle into the region caudo-central to the otic capsule. Section through anterior end of transplanted eye showing position of optic nerve-fibers. The optic nerve is projected into this section in part from the adjoining section. x 90 diameters.

Fig. 16. Experiment DF₁₇. Section 30 micro mm. caudal to one in figure, showing optic nerve-fibers leaving retina and running among the cells of the outer layer. X 360 diameters.

Fig. 17. Experiment DF₁₇. Section 50 micro mm. caudal to above, showing optic nerve-fibers close against the outer layer. > 360 diameters.

Fig. 18. Experiment DF₁₇. Section 30 micro mm. caudal to above, showing similar position of optic nerve. X 360 diameters.

Fig. 19. Experiment DF₁₇. Section 40 micro mm. caudal to above, showing optic nerve running from outer layer into medulla caudal to otic vesicle. The optic nerve-bundle can only be followed a few sections in the medulla. x 360 diameters.

Fig. 20. Experiment DF₁₀₄. -Embryo rana palustris killed 19 days after transplantation of the optic vesicle into the region between the eye and the otic vesicle. Section through middle of transplanted eye and side of brain. The transplanted eye shows invagination and differentiation of the layers of the retina, the cup cavity and pupil are much smaller than normal, and there is no trace of a lens. The ganglionic layer bordering the cavity has in places only a few scattered cells as most of the cells form a heap projecting into the cavity and from this heap of cells a nerve arises which passes across the cavity through the narrow pupil out into the mesenchyme to the subectodermal pigment band. There is also a small optic nerve passing through the retina into the outer layer, the figure shows its position here as projected from the two neighboring sections. It can be traced for a short distance only in the outer layer. X 90 diameters.

Fig. 21. Experiment DF₈₅. Embryo rana palustris killed 18 days after transplantation of the optic vesicle into the region between the otic capsule and medulla. Section through transplanted eye, otic capsule, and medulla. The eye, owing to irregular invagination, has only a very narrow pupil and small, irregular cup cavity. Most of the optic nerve-fibers pass from the irregular ganglionic layer through the narrow pupil into the mesenchyme ventral to the otic capsule, where it splits into two divisions, the ventral one of these runs a short distance and ends abruptly in the mesenchyme, the other runs to the cartilage ventral to the otic vesicle and can be traced for a short distance along it. The peripheral portion of the nerve, as shown in the figure, is projected into the section from the neighboring sections. Another portion of the optic nerve, smaller than the first one, runs through the retina and seems to end abruptly at the pigment layer. This portion of the nerve has also been projected into the figure from a neighboring section. > 90 diameters.
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