Morphology of Specialized Cells in Chick Ampulla

Abstract

The ultrastructures of the specialized cells in the ampulla were compared in chicks and guinea pigs. All the chick dark cells in the crista ampullaris were columnar in shape and had stereocilia on their apical surfaces. Many pinocytic vesicles containing dense substance were observed in the apical cytoplasm of the dark cells. The light cells, especially in the upper region of the eminentia cruciata, contained much expanded rough endoplasmic reticulum, which was filled with moderately electron dense material. These structures resembled those of the supporting cells in the sensory epithelium which participate in the formation of the cupula. The ultrastructures of the transitional cells of guinea pigs corresponded closely to those of the light cells. The tubulo-cisternal endoplasmic reticulum (TER) was present in all the specialized cells of both chicks and guinea pigs. The TER in the light cells was more developed than that in the dark cells. The ultrastructures of the cells of the planum semilunatum were not significantly different in the two animal species. It is concluded that morphologically the specialized cells of both chicks and guinea pigs consist of light cells, dark cells and cells of the planum semilunatum.