388 HISTOLOGY. 



by a triangular intercellular space or "tunnel." The space is filled with 

 soft intercellular substance. Thus they rest upon the basilar membrane 

 in A-form. The inner pillar cells are said to be more numerous than the 

 outer. Both forms are stiff bands with triangular expanded bases, which 

 are associated with nucleated masses of protoplasm within the "tunnel." 

 The "heads" or upper ends interlock, since the inner pillars are concave 

 to receive the convex surface of the outer pillars. From the superficial 

 surface of both, plates extend peripherally or outward, that of the inner 

 pillar partly covering the head-plate of the outer pillar (Fig. 438). The 



Nerve. 



Vas spirale 



Inner 



Outer 



Membrana Tympanal 

 Nuel's Deiters's basillaris. lamella, 

 cells. 



Pillar cells. 



FIG. 438. DIAGRAM OF THE STRUCTURE OP THE BASAL WALL OP THE DUCT OF THE COCHLEA. 

 A, View from the side. B, View from the surface. In the latter the free surface is in focus. It is 

 evident that the epithelium of the sulcus spiralis, lying in another plane, as well as the cells of 

 Claudius, can be seen distinctly only by lowering the tube. The membrana tectoria is not drawn. 

 The spiral nerve bundles are indicated by dots. 



dark bodies in the heads of both pillars, and in the basal part of the outer 

 ones, are not nuclei. 



On the peripheral side of the outer pillars there are several rows 

 (usually four) of outer hair cells separated from one another by sustentac- 

 ular cells (Dieters's cells). The outer hair cells have shorter hairs than the 

 inner ones, which otherwise they resemble. They do not extend to the 

 basilar membrane, thus leaving unoccupied the communicating inter- 

 cellular (Nuel's) spaces between the deeper portions of the sustentacular 

 cells. Nuel's spaces connect with the tunnel. The sustentacular cells 



