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From Embryology

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Fig. 29. Median view of left membranous labyrinth and the periotic spaces in a human fetus 85 mm CRL

Median view of wax-plate reconstruction of the left membranous labyrinth and the periotic spaces in a human fetus 85 mm. crown-rump length (Carnegie Collection, No. 1400-30), enlarged 11.4 diameters.

The scala tympani is shown in orange. The oval indentation in its proximal end corresponds to the fenestra cochlea (rotunda). This space extends along the cochlear duct about the same distance as the scala vestibuli, but the two do not commuinicate yet at any place. The peripheral border of the scala tympani is characterized by sacculations corresponding to spaces that are coalescing with the main space. The growth of the scala is due to a coalescence of new spaces along its peripheral border rather than along its central border.


The figures shown on this plate 4 represent a series of median and lateral views of wax-plate reconstructions of the membranous labyrinth and the surrounding periotic tissue-spaces. They illustrate under the same scale of enlargement three typical stages in the development of these spaces.

Abbreviations

  • C. s. 1. - ductus semicircuiaris lateralis
  • C. s. p. - ductus semicircularis posterior
  • C. s. s. - ductus semicircularis superior
  • Duct, coch., = ductus cochlearis
  • Impressio rotund. - area opposite the fenestra cochleae
  • Impressio staped., area in contact with base of stapes
  • Saccus endol. - saccus endolymphaticus
  • Scala tymp. - scala tynipani
  • Scala vestib. - scala vestibule.
Links: Plate 4 | Fig.26 | Fig.27 | Fig.28 | Fig.29 | Fig.30 | Fig.31


Reference

Streeter G.L. The histogenesis and growth of the otic capsule and its contained periotic tissue-spaces in the human embryo Contributions to Embryology Carnegie Institution No.20 (1918) pp5-54, 4 text-figures and 4 plates.

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current21:52, 22 April 2012Thumbnail for version as of 21:52, 22 April 2012774 × 1,000 (74 KB)Z8600021 (talk | contribs)====Fig. 29==== Median view of same model shown in figure 28, enlarged 11.4 diameters. The scala tympani is shown in orange. The oval indentation in its proximal end corresponds to the fenestra cochlea (rotunda). This space extends along the cochlear duct