Anatomical Features of the Planum Semilunatum on the Crista Ampullaris

Abstract

Anatomical peculiarities of the planum semilunatum on the crista ampullaris were studied using 20 pigeons. Animals were sacrificed by decapitation and prepared histologically, for SEM and TEM.
1) On the vertical crista ampullaris The planum semilunatum showed a semilunar distribution on the bilateral vertical crista ampullaris with taller cylindrial cells in the center and cells of decreasing height both in the periphery and running under the angle of the sensory cells in the center portion of the septum cruciatum. The supranuclear region of these cells contained small vacoules and granular materials. Intercellular space demonstrated well developed interdigitation.
2) On the lateral crista ampullaris The planum semilunatum was demonstrated only on one side of the crista, i. e. toward the superior crista ampullaris. This observation was not previously demonstrated. The planum semilunatum running under the angle of the sensory cells, however, did not reach the other side of the crista ampullaris. This observation confirmed the findings of Nomura and Hiraide.