238 



THE ESSENTIALS OF HISTOLOGY 



feet may usually be seen the remainder of the cells from which they 

 have been formed. The inner rods are narrower and rather more 

 numerous than the outer. Each outer rod has a process which extends 

 outwards and is known as the phalangeal process. This forms part 

 of 



2. A reticular lamina (fig. 279, l.r.), which is a cuticular structure 

 extending like a wire-net over the outer epithelium-cells of the organ 

 of Corti, and is composed of two or three series of stiff fiddle-shaped 

 rings (phalanges) cemented together in such a manner as to leave 

 square or oblong apertures through which the hair-cells (see below) 

 project. 



8. The outer Jiair-cells placed external to the rods of Corti. These 

 are epithelium-cells of columnar shape, arranged in three or four series 



T r 



FIG. 278. SECTION OF THE OKGAN OF CORTI OF THE DOG. ^aa 



, a', end of spiral lamina ; b, c, middle (homogeneous) layer of the basilar membrane ; u, ves- 

 tibular (striated) layer ; v, tympanal (connective-tissue) layer ; d, blood-vessel ; /, nerves 

 in spiral lamina ; g, epithelium of spiral groove ; h, nerve-fibres passing towards inner hair- 

 cells, i, * ; /, auditory hairlets on inner hair-cells ; I, I', lamina reticularis ; m, heads of the 

 rods of Corti, jointed together ; n, base of inner rods ; o, base of outer rod ; p, g, r, outer 

 hair-cells ; t, lower ends of hair-cells ; tr, nerve-fibrils passing across the tunnel of Corti ; 

 z, cells of Deiters. 



(fig. 278, p, q, r}. The free extremity of the cell is surmounted by a 

 bundle of short auditory hairs, and projects through one of the 

 apertures in the reticular lamina ; the fixed extremity is prolonged 

 into a stiff cuticular process (fig. 280, pf), which is attached to the 

 basilar membrane. Between them are other supporting cells which 

 are tapered in the same manner, resting by their larger end upon the 

 basilar membrane, and prolonged above into a cuticular process which 

 is attached to the reticular lamina (cells of Deiters, fig. 278, z).- They 

 are said by Waldeyer to be sometimes united with the outer hair- cells, 

 so as to form double cells. 



4. The inner hair-cells (fig. 278, i), placed internal to the rods of 



