Fig. 3

First-stage larvae (L1) and vitelline membrane of Stephanofilaria stilesi, bovine, skin. Transmission electron microscopy (TEM). a Two parasitic sacculi lined by vitelline membrane containing cross sections of larva (white arrow) and “eosinophilic disk” (black arrow) suspended in a matrix (m). Parasitic vitelline membrane and surrounding inflammation; proteinaceous material (Pd), plasma cells (Pc), macrophages (M), degranulated mast cells (arrowheads). Scale bar = 20.0 µm. b Vitelline membrane of the parasite (white arrows) and surrounding thick deposit of a granular/fibrillary material. Scale bar = 2.0 µm. Inset: magnification of the “vitelline membrane;” external and internal layers (white arrows), middle (layer black). Scale bar = 0.5 µm. c Sagittal section of a larva: cuticle (white arrows), somatic cells (SC), muscle cell (MC), parasitic matrix (m). Scale bar = 1.0 µm. Inset: magnification of the cuticle displaying its trilaminar structure. Scale bar = 0.25 µm. d Cross section of a L1 larva: cuticle (white arrows), somatic cells (SC), parasitic matrix (m). Scale bar = 2.0 µm. e “Eosinophilic disk” and elongated core (B) surrounded by electrode amorphous material. Scale bar = 0.5 µm