Figure 2.

Study of nephrocyte ultrastructural morphology using electron microscopy. The schematic illustrates a surface detail of a nephrocyte. Shown are labyrinthine channels as membrane invaginations that are sealed by the slit diaphragm. (A) The analogy to podocyte ultrastructure is most obvious in sections that are perpendicular to the nephrocyte surface. The slit diaphragm is recognizable as a fine line next to the electron-density around the entry to the membrane invagination. (B) Tangential sections through the surface show the slit diaphragm as continuous lines. This fine linear pattern correlates with the findings by confocal microscopy and staining of the ortholog of nephrin, sns (inset). (C) Perpendicular sections through the nephrocyte surface may be confusing when they cut through the nearly parallel lines of the slit diaphragms at an oblique angle. This results in an image that makes it difficult to identify the slit diaphragms and labyrinthine channels. Stretches of electron-density below the surface are mere indicators of their presence. SD indicates slit diaphragm, LC indicates labyrinthine channels, scale bars represent 500 nm.