DEVELOPMENT OF THE MEMBRANA TECTORIA 



427 



and Hammerschlag ('98) assert that it arises independently as a 

 coagulum or concretion of the endolymph, and later becomes 

 attached to the epithelium. Ayers ('92) maintained that the 

 fused hairs of the auditory cells form the membrana tectoria and 

 that their agglutinated tips later fuse to the labium vestibulare, 

 while Bottcher ('70) asserts that it is formed from hairs arising 

 from the epithelial cells of the cochlear duct. Coyne et Cannieu 

 ('95) found that the membrane was attached to the organ of 

 Corti or had been torn away from it and that it shows a lamellar 

 or reticular structure according as it is sectioned through the 



liinlnis 



ncmhraTia tectoria 



outer hair-cells 



7urve_fibres 



inner rod vat basilar outer cetla of Deittrt 

 *pimlr. membrane rod 



Fig. 1 Semi-diagrammatic representation of the organ of Corti antl adjacent 

 structures (Merkle-Henle). 



axis (modiolus) of the cochlea or in a plane perpendicular to 

 this. There are thickenings at the angles of the reticulum and 

 these thickenings give to the membrane the striated appearance 

 which is seen in other sections. 



Rickenbacher ('01) after studying five stages in the develop- 

 ment of the cochlea of the guinea-pig concludes that there are 

 two epithelial ridges (wuelste) in the floor of the cochlear duct. 

 The inner axial ridge is the greater and its cells give rise, first, 

 to the major part of the membrana tectoria as a cuticular secre- 

 tion which increases in thickness outwardly by the addition of 

 new lamellae. Later from these cells are formed the epithelium 



THE AMERICAN JOURNAL OP ANATOMY, VOL. 14, NO. 4 



