A comparative study of the tissue response to invasion and encystment by Stephanochasmus baccatus (Nicoll, 1907) (Digenea: Acanthocolpidae) in four species of flatfish

• Published in: Journal of Fish Diseases
• Main Author: SOMMERVILLE, CHRISTINA
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1981
• Subjects: Dover; Scophthalmus maximus; Turbot
• Online Access: http://dx.doi.org/10.1111/j.1365-2761.1981.tb01109.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1365-2761.1981.tb01109.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-2761.1981.tb01109.x

Abstract. Four species of flatfish [plaice, Pleuronectes platessa L.; turbot, Scophthalmus maximus (L.); Dover sole, Solea solea (L.) and the common dab, Limanda limanda (L.)] were experimentally infected with cercariae of Stephanochasmus baccatus under similar conditions and examined at intervals up to 7 weeks post‐infection‐ The tissue response was found to be qualitatively the same in all four hosts and was consistent with a chronic granulomatous inflammatory reaction induced by resistant particulate foreign bodies. The intensity and rate of the response varied between host species but the capsule formation was essentially similar in all. The mature capsule consisted of an inner layer composed of leucocytes which underwent epithelioid transformation. The cellular structure of this tissue gradually degenerated from the oldest layer to form a dense eosinophilic ground substance in which was embedded nuclear debris. The outer layer of the capsule consisted of fibroblasts and reticulin collagen fibres. Muscle and fin cysts differed, with muscle cysts tending to be less discrete and more fibrous. The rate and intensity of the response to the parasite varied between different host species. Plaice and turbot showed the most intensive response and in turbot the reaction was considerably accelerated. Mortality of encysted metacercariae was only seen in turbot. The overall effect on larger 1‐group fish was minimal, but the smaller 0‐group plaice were more severely affected by the relatively large cvsts that interfered with organ function.