High Resolution Helium Ion Scanning Microscopy of the Rat Kidney
(A) Luminal surface of an outer medullary collecting duct (GA-fixation, dehydration using the rapid graded methanol procedure) showing principal and intercalated cells. Each principal cell (PC) has one long, solitary cilium (arrows) and numerous short, stubby microvilli. The intercalated cell (IC) has numerous elaborate apical microplicae and no cilium. Bar = 2 µm. (B) High magnification view of a principal cell cilium (Bar = 200 nm). At its base, a concentric pattern of surface protrusions (arrows) can be seen in the position of the ciliary necklace. A similar structure is shown on another principal cell cilium in the inset (arrows, Bar = 100 nm). A principal cell cilium from the same kidney was also imaged by conventional SEM without sputter coating, using an in-lens detector (C). Structural details of the cilium, ciliary necklace, microvilli, and membrane indentations are more clearly distinguishable in the HIM than in the SEM images. Bar = 300 nm.