388 



THE PERIPHERAL NERVOUS SYSTEM 



n. each. 



Fig. 386. — Three stages in the differentiation of tlie basal epithelium of the cochlear duct to form 

 the spiral organ (of Corti), internal spiral sulcus and labium vestibulare. .1, Section through the coch- 

 lear duct of an 8.5 cm. pig fetus (X 120); B, the same from a 20 cm. fetus (X 140); C, from a 30 cm. 

 fetus (near term) (X 140). ep.s.sp., Epithelium of spiral sulcus; h.c, hair cells; i.ep.c, inner epithelial 

 thickening; i.h.c, inner hair cells; i.pil., inner pillar of Corti; lab. vest., labium vestibulare; limb, sp., 

 limbus spiralis; m. bas., basilar membrane; m. led., membrana tectoria; m. vest., vestibular membrane; 

 n. coch., cochlear division of acoustic nerve; o.ep.c, outer epithelial thickening; o.li.c, outer hair cells; 

 s.sp., sulcus spiralis; sc.tymp., scala tympani; st.H., stripe of Hensen; t.sp., spiral tunnel. 



