Forms and ultrastructural features of the lateral alae of the helminth Trichostrongylus tenuis Mehlis, 1846 (Nematoda: Trichostrongylidae)

Abstract

Ultrastructural features of the nematode Trichostrongylus tenuis were studied. Helminthological studies were carried out in the Nakhchivan Autonomous Republic in 2015–2018. The material from domestic waterfowl was collected by the method of complete parasitological dissection. Along with the fact that this helminth is a specific parasite of domestic waterfowl, it dominates among all the types of helminths noted by us and is the cause of serious changes in the host organism. The study of the ultrastructure of the nematode T. tenuis is important for identifying parasitic-host relationships, clarifying the systematic position of parasites and in preparing measures to combat these parasites. In addition, a wide variety of morphological features of the lateral alae, allows them to be used as one of the main features for identifying helminth species. The article first presents data on the ultrastructural features of the lateral alae of the nematode T. tenuis. As a result of the studies, it was found that, despite the fact that in some parasitic nematodes of the Trichostrongylidae family the morphological structure of the lateral alae of the cuticle is identical over the entire surface of the body, in the nematode T. tenuis belonging to the same family, four forms were revealed during ultrastructural studies, which were represented using diagrams and electron diffraction patterns. Lateral alae consist of cortical, homogeneous, and fibrillary layers differing in size, thickness, and other features. From the front (oral) part of body of the nematode T. tenuis to the beginning of the intestine, the cuticle is smooth; on the body part from the small intestine and behind it, lateral alae begin to be observed, which resemble a “ridge” in shape. When approaching the posterior end of the body, the lateral alae take the form of “hooks”. On the caudal region, the lateral alae become even more complicated and get the form of “spikes”, and relatively small outgrowths are additionally observed on these lateral wings. These signs can be used to clarify the taxonomic position of helminth species.