Transmission Electron Microscopy of Intracellular Sporozoites of Eimeria vermiformis (Apicomplexa, Eucoccidiida) in the Mouse¹

Abstract

Sporozoites of Eimeria vermiformis from the mouse were first seen in the epithelial cells of villus tips and the crypts of Lieberkühn four hours after inoculation (HAI). They were always within a parasitophorous vacuole. By 12 HAI, most were in crypt epithelial cells between the basement membrane and host cell nucleus. The sporozoites in the villus tips had 26 subpellicular microtubules, two polar rings, two preconoidal rings, two refractile bodies surrounded by amylopectin-like granules, a lamellar Golgi apparatus, numerous micronemes, and rhoptries. The sporozoites in the crypt cells had fewer amylopectin-like granules, micronemes, and rhoptries. A nucleolus was visible, as were pieces broken off from the posterior refractile body. Later, the sporozoites folded over to become U-shaped; the infolded membranes fused; and then the inner membranes disappeared so that spherical meronts were formed. Folding sporozoites were first seen 16 HAI and persisted until 52 HAI.

Transmission Electron Microscopy of Meront Development of Eimeria vermiformis Ernst, Chobotar and Hammond, 1971 (Apicomplexa, Eucoccidiorida) in the Mouse, Mus musculus1

“…Techniques used were those reported earlier (1). Tissue samples were taken from mice necropsied at 20, 24,28,32,36,40,41,42,43,44,45,48,52,56,60,64,68,71, and 76 h after inoculation (HAI).…”

“…(3), this study presents some developmental characteristics that have not been described extensively or to date are unique to Eimeria vermiformis. The only other ultrastructural study of E. vermiformis has been of the intracellular sporozoites (1). Blagburn et al (2) recently described by light microscopy the first generation of E. vermiformis.…”

Cytoskeleton of Apicomplexan Parasites

“…3A and a). The subpellicular microtubules radiate from the apical polar ring and run down the cytosolic face of the pellicle, ending in the region below the nucleus (approximately two-thirds of the length of the parasite [1,12,13,26,31,120,131]). These spirally arranged microtubules closely follow the serpentine body shape of apicomplexans.…”