Abstract
The supposed similarities between the large pit organ and lateral-line canal organ were confirmed by the present investigation: the receptor cell is provided with sensory hairs which are arranged in a characteristic pattern, described in the receptor cell of the canal organ, and are innervated by two kinds of nerve endings, i.e., nongranulated and granulated, although the former appears more frequently than the latter.The supporting cells which may have sustentacular function and secretory activity are divided into two kinds, the central and peripheral, mainly on the basis of their topographic position in the large pit organ.While these two kinds of the supporting cells show no remarkable differences in their basic structure, the size and shape of secretory granules found in the apical cytoplasm are different between them.Whether such morphological differences of the granules correspond to the differences of chemical natures of substances contained in the granules or not is the subject of future research.
