Fig. 3

Comparison of light (LM) and transmission electron microscopy (TEM) photomicrographs of Sarcocystis arctica (a, c) and S. lutrae (b, d) from the red fox (Vulpes vulpes). a LM micrograph showing thin-walled cyst, with barely defined villar protrusions (vp, arrowheads); note bradyzoites (br) and muscular host cell (hc). H&E-staining. b LM micrograph showing well-defined thin cyst wall, with minute undulation due to fixation (arrowheads); note bradyzoites (br) and septum (se). H&E-staining. c TEM micrograph showing details of villar protrusions (vp), the total width of cyst wall (cw), ground substance (gs) with few electron-dense granules, and invaginations (arrowheads) of the electron dense layer (edl); note, details of bradyzoites (br), nucleus (nu) and conoid (co). d TEM micrograph is showing details of the simplest structure among cyst walls types within genus Sarcocystis, smooth ground substance (gs), blebs (arrows), invaginations (arrowheads), septum (se) and bradyzoite (br) with defined microtubules in conoid (co). Scale-bars: a, b, 10 μm; c, d, 1 μm