When only secondary antibodies were applied no gold labeling
of the microvilli-rich apical area of GFE cells was detected
(Fig. S2A). In addition, only sporadic gold particles were detected
in hemocytes (Fig. S2B, left image) or nuclei (example in
Fig. S2B, right image), structures that are unrelated to the
epithelial secretion pathway, as opposed to numerous gold
particles seen in the adjacent cytoplasm and membrane
systems.