Description of Plates II
|The reproductions shown on this plate represents different views, lateral, front, and median, of a selected model showing the membranous labyrinth and acoustic complex reconstructed from the following human embryo No. 86, 30 mm. The drawings for Plates I and II were prepared under the guidance and assistance of Mr. Max Brodel.
The colors, yellow and red, are used to indicate respectively the cochlear and vestibular divisions, and in general nerve flbers can be distinguished from ganglion cell masses by their lighter tone. The pictures represent a magniflcation of 25 diams.
The last step in its differentiation consists in the widening of the distal end into a flattened pouch or sac, in contrast to the remainder, which persists as a narrow duct connecting it with the vestibule, indicated in Figs. a, b, c, Plate II.
The thickness of the epithelium of the outer edge and presence of division figures indicate that the activity of growth still continues. Section D shows a canal in an embryo 30 mm. long, the same stage as that shown in Figs. a, b, c, Plate II.
The initial ingrowth of the membranous partition can be seen in Figs. 1 and m, where it can be distinguished as a horizontal cleft which forms in front between the utricular and saccular parts of the atrium. Strictly speaking we cannot speak of a saccule and utricle until the intervening partition is complete. It is practically complete in Figs. a, b, c, Plate II; here it reaches back to the entrance of the ductus endolymphaticus. It later divides the orifice of that structure, thus affording it separate openings into the utricle and saccule, the two openings constituting the so-called ductus utriculo-saccularis.
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- Mall 1906 Links: Fig 1. 14mm Embryo | Fig 2. 30mm Embryo | Fig 3. Semicircular canal | Fig 4. Membranous Labyrinth | Fig 5. Acoustic nerve complex | Fig 6. Facial-acoustic Complex | Fig 7. Facial Nerve Pig Embryo 20 cm | Fig 8. Geniculate Ganglion | Plate 1. Human Embryo 4 to 20 mm | Plate 2. Human Embryo 30 mm | Membranous Labyrinth and Nerves
Cite this page: Hill, M.A. (2019, March 26) Embryology Streeter1906 plate02.jpg. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/File:Streeter1906_plate02.jpg
- © Dr Mark Hill 2019, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G
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