Circulatory system of rainbow trout Oncorhynchus mykiss (Walbaum): a corrosion cast study

Abstract

Summary The present study describes and visualizes the circulatory system of rainbow trout with emphasis on the heart and main blood vessels, employing corrosion cast methodology. Ten rainbow trout (Oncorhynchus mykiss (Walbaum) of 1000 g average weight were obtained from a commercial fish farm. Fish were anaesthetised using a benzocain solution in ethanol. After 40 min, the fish were killed using an overdose of the benzocain solution. The aorta caudalis and aorta coeliaco-mesentric were cannulated and attempts were made to fill the blood vessels and heart with fluid artificial resin made on the basis of methylmetacrylate. The fish were further prepared by submersion for 12–24 h in a room temperature waterbath until polymerisation and hardening of the methylmetacrylate was complete. This was followed by 24–48 h submersion in a 25% solution of KOH to obtain full maceration of the organic tissues. Various parts of the heart and blood vessels were retained in their natural positions, thereby demonstrating the anatomical details of the main circulatory system. Main elements depicted included the sinus venosus, atrium, ventricle, bulbus arteriosus and related vessels such as the dorsal aorta, subclavian vein, hepatic vein, common cardinal vein, coeliaco-mesenteric artery, gastero-intestinal artery, and dorsal intestinal artery. Related smaller vessels were also determined.