ニジマス耳石器官におけるカルシウム-45の挙動

抄録

Calcium-45 incorporation and its turnover were examined at the level of the otolithic organs of some rainbow trout.
The intraperitoneally-injected isotope showed maximum incorporation into both the serum and otolith fluid within 3 hours after injection. Thereafter the radioactivity in the serum decreased rapidly and that in the otolith fluid gradually. On the contrary, the isotope deposited on the otolith (sagitta) increased with the lapse of time up to 72 hours, which was the final examination time. In this case a heavy accumulation was found to occur not on its lateral surface but on its medial surface where the otolith stands close to the macular cells of the sacculus. Autoradiographic visualization also confirmed such a distribution pattern of the isotope on the otolith. In addition to these facts, judging from the heavy appearance of the isotope in an autoradiogram of the medial macula, the calcium which takes part in the otolith formation seems to be supplied, at least in part, through this region. Some squamous cells of the saccular wall were also positive to radiocalcium.