Electron microscopy of <i>L</i>. <i>stagnalis</i> mantle tissue sections.

<p><b>(A)</b> Low magnification image with rhogocytes (rc), muscle cells (mc) and granular cells (gc). <b>(B)</b> Medium magnification showing a single rhogocyte; note the big nucleus (n), endoplasmatic reticulum (er) and electron-dense granula (g). The white frame indicates the area magnified in (C). <b>(C)</b> Close-up of an area with extracellular lacunae (e), cytoplasmic bars (b), and diaphragmatic slits (s) shown in longitudinal cuts. (<b>D</b>) Another single rhogocyte; the frame indicates the area magnified in (E). (<b>E</b>) Close-up of the area marked in (D), with a further magnification (frame) presented in the insert. It shows the cytoplasmic bars (b) and diaphragmatic slits (s) in a transversal cut. The extracellular lacunae (e) are filled with granular material. Note at both ends of the cytoplasmatic bars the electron-dense material (a). This material is likely to contain actin (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0141195#pone.0141195.g007" target="_blank">Fig 7</a>). (<b>F</b>) Another rhogocyte. Note the magnified slit apparatus in the (white box), and the coated vesicle (cv) fused with the extracellular lacuna (black box).