Uptake of tritiated leucine by the prolactin cell follicles of the coho salmon, Oncorhynchus kisutch

摘要: Uptake of tritiated leucine during various time intervals by prolactin cell follicles of coho salmon (Oncorhynchus kisutch) acclimated to 30‰ artificial seawater was studied. Labelling in eta cells from fish transferred to freshwater immediately after injection was higher than in fish remaining in 30‰ seawater. Grains in individual eta cells were evenly distributed with the exception of some follicles where there were higher concentrations at the apical ends. This was interpreted as indicating the initial stage of active incorporation of leucine in the juxtaluminar region. Freshwater fish exhibited not only higher grain density but also apical grain concentration at earlier times than seawater fish, suggesting faster uptake and (or) incorporation of leucine, and therefore presumably of prolactin production, in the freshwater fish. No labelling was found in the follicular lumina except when hematoxylin-stained bodies were found in the lumina of adjacent sections of stained follicles. The significance of these bodies is unknown but it appears unlikely that the lumina are involved with the synthesis of prolactin.