134 ARRANGEMENT AND STRUCTURE OF SUSTENTACULAR CELLS 



in direct contact with the bars, and described by Joseph (1900) as " Einschliissen " 

 of the heads of the inner and outer rods of Corti. 



The supporting apparatus of the cells of Deiters, its stem or paraxial, fibrillar 

 bundle, and its two branches the apical filament and the axial strand with the 

 chalice is laid down by the original mitochondrial band extending throughout the 

 length of the outer sustentacular elements (fig. 4, d\ d", d iis ). The chondriomites 

 of this strand are clearly illustrated in figures 9 and 19 (d 1 , d", d iu ). By a process of 

 coalescence of the chondrioconts (fig. 10, d 1 , d", d 1 ") the fibrils of the apical (fig. 21) 

 and of the paraxial, medial (figs. 25 and 16, d 1 , d", d" 1 ) filaments are produced. The 

 axial filament, with its chalice, appears in more advanced stages, when the segment 

 of support of the cell of Deiters becomes enlarged and elongated below the hair-cell. 

 At this time a long, axial, compact, and mitochondrial band is formed within the 

 upper part of the nucleated cell body (fig. 23, d 1 ), and by accumulation and coales- 

 cence of the chondrioconts the short axial filament, along with its superficial chalice, 

 is built up (fig. 11, d 1 , d", d m ). The chondriosomes of this axial part of the segment 

 of support of the sustentacular elements have been described by Retzius (1900, p. 

 80), as "eine schwarz gefarbte Korneransammlung," which do not represent centro- 

 somes and bear no relation to filaments. After examining these preparations M. 

 Heidenhain stated that the granules may be either multiple, central corpuscles, or 

 structures analogous to the " Basalfilamente " in other cells. 



Besides their supporting apparatus, the cells of Deiters are composed of a much 

 more abundant, clear, and often distinctly vacuolated (figs. 5, 7, 9, and 11) cyto- 

 plasm, which is less conspicuous within their phalanx process, although recognizable 

 in some preparations (figs. 5 and 14). The paraxial filament always occupies the 

 medial half of this vacuolated protoplasm (fig. 16, d 1 , d", d m ), and the latter be- 

 comes reduced around the axial band and its chalice (fig. 23, d'), when these struc- 

 tures make their appearance. 



From the above description it is clear that the fibrillar framework of the rods of 

 Corti and of the cells of Deiters appears in the earliest stages of development and 

 is mitochondrial in nature. Similar filamentous structures have been described 

 in lining epithelium cells by Firket (1910), Favre and Regaud (1910), and Sakae 

 Saguchi (1913). The fibrillated apparatus and vacuolated cytoplasm of the sus- 

 tentacular cells seem to be related to two different functions of these elements, the 

 former to an absolutely conspicuous supporting function, the latter to a nutritive 

 function. In order to get a true picture of the capacity of nutrition of the rods of 

 Corti and the outer supporting cells, we should bear in mind that during the earliest 

 stages of development of the organ the epithelial constituents undergo a rapid 

 enlargement. Peculiar and complex structures the superficial cuticula with its 

 hairs, the membrana reticularis, and a part of the membrana tectoria spring from 

 the surface of the neuro-epithelium, which is destitute of blood-capillaries. There 

 exist no intercellular channels to convey the nutritive material from the subjacent 

 vascular tissue of the membrana basilaris to the superficial portions of the epi- 

 thelium. Minute intercellular spaces undoubtedly exist, and their cement gives 



