Development of the tectal cells in the mouse cochlea.

Tectal cells appear at birth in the outer part of the developing organ of Corti. At first they are attached to the basilar membrane, but later they ascend through the auditory epithelium. During the 1st postnatal week (coinciding with the development of the minor tectorial membrane), the newly formed tectal cells show several cytological characteristics suggesting increased metabolic and secretory activities, which include: (1) a large Golgi complex, (2) abundant amorphous material inside the cisterns of rough endoplasmic reticulum, and (3) dense granules inside the mitochondrial matrix. All these features gradually disappear, and by the 14th postnatal day the tectal cells show a dark cytoplasm and few and short microvilli. In addition, tectal cells were stained selectively by some lectins. These findings suggest that tectal cells may participate in the secretion of some components of the minor tectorial membrane, different from those produced by Deiters' cells, Hensen's cells and pillar cells.