Book - Contributions to Embryology Carnegie Institution No.31
The Arrangement And Structure Of Sustentacular Cells And Hair-Cells In The Developing Organ Of Corti
By 0. Van der Stricht,
Professor of Histology and Embryology, Universily of Ghent, Lecturer in Anatomy, Johns Hopkins University.
With four plates.
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Introduction
The arrangement of the outer sustentacular and hair-cells of the organ of Corti in adult mammals is rather well known. According to the investigations of Held (1902), N. Van der Stricht (1908), and Kolmer (1909), the body of the cell of Deiters is situated below that of its sensory element, so that the two are connected by a chalice-shaped, greatly modified segment, in the concavity of which hes the deep cytoplasmic portion of the supported hair-cell. In the embrj'onic stages, however, the relation between these two elements is entirely different, and it might be well worth while to trace accurately their connections through the whole developmental stage. The same holds good for the inner and outer rods of Corti, the inner supporting cells, and even some of the so-called cells of Hensen.
Most investigators who have tried to clarify the arrangement of the sensory
and sustentacular elements in embryonic material have made use of and describe
vertical radial sections of the organ of Corti. Although very interesting, and in fact
highly necessarj^, such preparations are hable to be deceptive and lead to misinterpretation. Indeed, most authors incorrectly represent the cells of Deiters. Many
authors, even Retzius (1884) and Held (1909), who describe the phalanx process of
the sustentacular elements as running obliquely from the cell body towards the
lamina reticularis, thus crossing two or three hair cells, generally picture it in illustrations of vertical radial sections as an uninterrupted band connecting the nucle-
ated portion of the cell with the free surface of the epitheUum. So, also, do most
authors of text-books of histology, notwithstancUng the fact that in a radial vertical
section this protoplasmic strand shows at least three interruptions.
By making use of sections tangential and alwaj^s somewhat obUque to the surface of the organ of Corti, N. Van der Stricht was able to accuratelj' locate the nucleated body of the supporting elements in successive stages of development and to determine the amount of gradual shifting. In this stud}' the same method of research was apphed in order to locate the more superficial portions of these cells between the sense-epitheUum elements, and to ascertain their exact relation to the hair-cells and the mechanical factors that cause the shifting of the sustentacular elements. Moreover, a series of preparations, exhibiting mitochondrial structures in the supporting cells and hair-cells, has rendered it possible to define the nature of coarser structures noted by previous observers.
Methods
Kittens, dogs, and rabbits, from birth to 12 days old, white rat fetuses, and young white rats about 2 days old, constituted the material used in these investigations. The isolatetl cochlea was fixed by trichloracetic acid (5 per cent in water), by Bouin's or by Zenker's fluid, and subjected for many weeks to the mordant action of some drops of iodine in alcohol (70 per cent). Where necessary, after fixation by Bouin's or by Zenker's fluid, decalcification was completed by 2 per cent nitric acid in 70 per cent alcohol. Before embedding in paraffin the pieces were stained with borax carmine and the sections with iron hematoxylin, Congo red, and light green.
The mitochondria in the sustentacular and hair-cells were fixed in the following manner: Mixture of formalin and bichromate of Regaud (1910), according to the modifications indicated by Cowdry (1916), and subsequent staining with acid fuchsin and methjd-green ; treatment by a 1 per cent aqueous solution of osmic acid for about an hour, followed by immersion in trichloracetic acid, or Bouin's or Zenker's fluid; exposure of the cochlea, the bony wall of which had been previously provided with two or three small o[)enings, to vapors from a 2 per cent a([ueous solution of osmic acid for approximately 30 to 60 minutes, and subsequent treatment of the piece by one of the three above-mentioned agents; fixation for an hour in a 1 per cent aqueous solution of osmic acid, followed bj' immersion in a 1 per cent aqueous solution of silver nitrate for 3 hours. By these methods of fixation, and staining with iron hematoxylin and Congo red, the mitochondria can be brought into prominence within one or two turns of the cochlea, occasionally throughout its extent. Osmic vajjors have been recommended as a fixing agent for mitochondrial structures by M. R. Ijcwis and W. H. Lewis (1914). We are able to confirm tins statement, having for many years successfully used these vapors, and a subsequent treatment by another reagent, for the purpose of fixing the chondriomites in the ova of the dog. Henneguy (1895) was able to bring into view chondrioconts in the spermatocytes of Helix by the use of osmic vapors.
The description given herein is illustrated by figures representing three different series of sections:
(1) Radial, vertical sections of tho organ of Corti. These are cross-sections of the rows of hair and supporting colls, the knife cutting the latter along their length and from the axis toward the outer wall of the cochlea (figs. 14, 15, and 16).
(2) Spiral, vertical sections of the organ of Corti, these being longitudinal sections of the parallel spiral rows, the knife cutting the hair and supporting cells along their length, from the more apical to the more liasal part of the sjiiral organ (figs. 19, 20, 22, and 23).
(3) Sections tangential and always somewhat oblique to the surface of the organ of Corti, the knife cutting transversely the hair and sustentacular cells of the spiral parallel rows at all levels, from the surface of the epithehum towards the basilar membrane (figs. 2 tf) 13, 17 and 18), so that their arrangement and structure can be traced in cross-sections throughout their lengths (figs. 2 and 3).
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Cite this page: Hill, M.A. (2024, June 21) Embryology Book - Contributions to Embryology Carnegie Institution No.31. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Book_-_Contributions_to_Embryology_Carnegie_Institution_No.31
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