360 



MANUAL OF HISTOLOGY. 



lagena, and ampulla frontalis ; those from the vestibular 

 branch go to the utricle and the ampullae of the horizontal and 

 sagittal semicircular canals. The termination of the nerves in 

 the saccule and utricle is called macula acustica, and in the 

 ampullae, crista acustica. 



The macula is a small, roundish spot, slightly projecting 

 above the surface. Thin sections through it show the presence 

 of three layers of cells. Directly upon the wall proper of the 

 canal lies a single row of small, round epithelial cells with 

 large nucleoli (Fig. 160, 1). Next come several rows of cells hav- 



cp. nerv. 



cartilage. 



Fio. 160. Section through the ampulla frontalis of esox lucius: 1, basal cells ; 2, cells with thread- 

 like prolongations ; 3, cylindrical cells, with cilia. After Knhn. 



ing a round or oblong (spindle-shaped) central portion, from 

 which are given off two filiform prolongations, the one passing 

 inward and standing in close connection with a fine plexus of 

 nerves lying in the layer of round cells mentioned above ; the 

 other also passing inward, but ending either as a free cilium 

 between the layer of cells next to be described, or being joined 

 to their inner extremity (Fig. 160, 2, and Fig. 161). 



The inner layer consists of several rows of cylindrical epi- 

 thelial cells, having the end, which is directed inward, tapering 

 into a fine filament connected with those of the middle layer, as 



