Microscopic Study of Mechanoreceptors and Chemoreceptors of Anterior and Posterior Ends of Toxocara Canis Using Scanning Electron Microscopy (SEM) and Light Microscope (LM)

Document Type: Original Articles


1 Department of Pathobiology, Faculty of Veterinary Medicine, Division of Parasitology, Urmia University, Urmia, Iran.

2 Department of Pathobiology, Faculty of Veterinary Medicine, Division of Pathology, Urmia University, Urmia, Iran.


In this study, fine structure of amphids and phasmids of Toxocara canis and cuticle, muscles and digestive tracts in this parasite were investigated using optical and electron microscopy and hematoxylin-eosin (H&E) staining as well as other specific stains. Thirty-eight adult T.canis worms were used in this study. These worms were collected from the small intestines of Urmia’s canines and fixated in AFA and 10% formalin solutions. The anterior and posterior part of T.canis male and female worms were prepared according to the conventional method in the histological laboratory and cut at 4-5 μm thickness. The samples were then stained using H&E and specific PAS, Masson's trichrome and Orcein staining and the structure of amphid (anterior), phasmid (posterior), cuticle, muscles and digestive tracts of male and female worms were studied under light microscopy. Basal, intermediate, cortex and cuticle surface coating of the parasite were visible. Alae are also seen as the thickenings in the cuticle. The muscle layer structure consists of non-branched cylindrical cells. The intestinal tract is composed of cuticular cogs, the esophagus is of filamentous-muscular structure, and the intestine is made of columnar epithelial tissue with microvilli and glycocalyx. The amphid structure consisted of cuticular protrusions with penetrations of cephalic framework to their inner layers. Phasmid structure also includes protrusions in the cuticle and invagination of sensory neurons. It was concluded that for the most part, the histological structure of the cuticle can be studied using optical microscopy. The muscle structure in this parasite is very similar to the skeletal muscle in mammals. Also, the epithelial structure of the intestine in this parasite was largely similar to the intestinal epithelium in mammals. Finally, in relation to the amphid and phasmid structure, it was observed that they were protrusions covered by cuticles where neural, filamentous and muscular structures were the core of these protrusions.