A STUDY ON FINE STRUCTURE OF SACCULAR MACULA OF GOLD FISH

The fine structure of the saccular macula of the gold fish has been studied by means of the electron microscope. The sensory epithelium of the macula consists of sensory cells and supporting cells. The surface of the sensory cell is studded with a group of sensory hairs consisting of one kino-cilium and 50-60 stereocilia. In the dorsal half of the macula, the kino-cilium is located at the dorsal end of the sensory hair group. In the ventral half of the macula, the kino-cilium is located at the ventral end of the sensory hair group. In the intermediary portion of the macula, the sensory cells with opposite polarities are situated side-by-side. The relation between the microphonic potential and the position of the kino-cilium has been discussed. Two types of nerve terminals are found situated on the basal surface of the receptor cells. The one contains no synaptic vesicle and the other contains a cluster of synaptic vesicles and a few cored vesicles. It is considered that the former corresponds to the afferent nerve terminal and the latter to the efferent one. © 1969 Springer-Verlag.