THE ARRANGEMENT AND STRUCTURE OF SUSTENTACULAR CELLS AND 

 HAIR-CELLS IN THE DEVELOPING ORGAN OF CORTI. 



BY 0. VAN DER STRICHT. 



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 lies the 

 deep cytoplasmic portion of the supported hair-cell. In the embryonic 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 devel- 

 opmental 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 necessary, such preparations are liable to be deceptive and lead to misinter- 

 pretation. 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 illus- 

 trations of vertical radial sections as an uninterrupted band connecting the nucle- 

 ated portion of the cell with the free surface of the epithelium. So, also, do most 

 authors of text-books of histology, notwithstanding the fact that in a radial vertical 

 section this protoplasmic strand shows at least three interruptions. 



By making use of sections tangential and always somewhat oblique to the sur- 

 face of the organ of Corti, N. Van der Stricht was able to accurately locate the 

 nucleated body of the supporting elements in successive stages of development and 

 to determine the amount of gradual shifting. In this study the same method of 

 research was applied in order to locate the more superficial portions of these cells 

 between the sense-epithelium 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. 



111 



