Fig. 1

Sarcocystis sp. obtained from the little grebe, Tachybaptus ruficollis. a A wet mount from esophageal muscles infected with sarcocysts stained with potassium alum carmine. Note the heavy infection with numerous ribbonlike sarcocysts (arrowheads). Scale bar = 1 mm. b Cross section of a thin-walled Sarcocystis sp. sarcocyst in a hematoxylin and eosin (HE)-stained histological section. Scale bar = 20 µm. c Transmission electron microscopy (TEM) image of Sarcocystis sp. showing zigzag-like or undulating vacuolar membrane with villar protrusions (VP) of slightly variant sulci and gyri. Scale bar = 1 µm. d A higher magnification of the TEM image reveals a cyst wall (CW) with several bleb-like protrusions (arrowhead), ground substances (GS), fragments of bradyzoites (B) with dense granules (DG) and septa (S). Scale bar = 0.5 µm