Abstract
The localization of rat small intestinal microvillous sucrase-isomaltase was studied by immunoelectron microscopy to investigate its intracellular transport to the microvillous membrane. At the same time, the usefulness of a rapid embedding method of tissues in Lowicryl K4M for immunocytochemistry of sucrase-isomaltase was examined. Sucrase-isomaltase was present not only in the microvillous membrane, but also in the apical vesicles and the apical plasma membrane invaginations. Negli-gible labeling was observed in the other portions of the absorptive cells. These findings suggest that the final step of intracellular transport of sucrase-isomaltase to the microvillous membrane is via smooth apical vesicles. The rapid immunoelectron microscopic method adopted in this study seemed to be a useful technique for the study of the intracellular localization of sucrase-isomaltase.
