Decreased transport of orally administered protein into the blood circulation of developing juveniles of Japanese eel Anguilla japonica

To clarify the quantitative changes in the transport of orally intubated pr otein into the blood circulation as macromolecules in development, immunogl obulin Y (IgY) extracted from chicken eggs was administered orally to juven ile Japanese eel, Anguilla japonica. For the first experiment, which was pe rformed before the commencement of artificial feeding, the oral delivery of 20 mug/0.1 g bodyweight of IgY resulted in a rapid increase in plasma IgY to a maximum of 2.30 mug/mL. However, the transport of IgY into the blood d ecreased significantly in the experiments that followed, which were perform ed after 12, 25 and 42 days. During this period, bodyweight increased appro ximately by a factor of eight, and rapid growth of the stomach was observed histologically. Possible contributions for the development of the alimenta ry canal to the diminishment of intestinal protein assimilation are discuss ed.