Abstract
The distribution of the tectal cells of the outer tunnel which was reported by Henson et al in 1983 was studied in golden hamster by scanning electron microscope. And the following conclusions were obtained as a result. 1) Between the third row of Deiters' cells and the most medial row of Hensen's cells, there is the area which has the different surface structure from two other cells and it is suggested to be tectal expansion. 2) This part shows a thin plate-like structure and forms the roof of the outer tunnel of the organ of Corti. 3) Tectal expansion is absent in the upper turn and begins to be recognized in the lower middle turn. In the basal turn, it shows a larger cell surface.
