Pitfalls in the double labelling immunoelectron microscopy using one face of the grid.

We compared two procedures in the double labelling immunoelectron microscopic method of hormone-storing cells: one-faced and two-faced procedures. With the two-faced procedure we got convincing results consistent with morphological finding, while we often got false results with the one-faced procedure. By the misleading one-faced procedure, the cell storing any one hormone will be misinterpreted as a multihormone storing cell. Therefore, it is concluded that the two-faced method is safer for the double labelling immunoelectron microscopic study.