AbstractBackgroundOne of the special anatomical structures in sturgeons is the pericardioperitoneal canal (PPC), which has not been studied much. Considering that the presence and absence of this channel and its morphometry have not been investigated in this type of fish, this study was conducted.ObjectiveThe purpose of present study was to obtain a complete understanding about anatomical features and ultrasonography of PPC in the heart of immature beluga species in order to provide standard approaches for performing sonography and echocardiography on this sturgeon species.MethodsTen immature belugas (Huso huso) were used to perform ultrasonography with Sonosite MicroMaxx ultrasonography machine of ventral approach between two pectoral fins. After performing the steps of ultrasonographic study, gross anatomical studies were also performed, and the morphometric measurement of the canal was also performed.ResultsA small PPC was observed, which communicated between the pericardial cavity, and the peritoneal (coelomic) cavity. The cranial part of this channel, which was located immediately after the transverse septum, was on the midline of the body and was seen in midsagittal ultrasonograms. On average, the length of this canal was 3.23 ± 0.05 cm, and its diameter (cranial part) was 0.24 ± 0.04 cm.ConclusionsIn the present study on immature beluga, it was observed that the canal is located behind the sinus venosus and is caudoventral to it, though behind the transverse septum. It has been mentioned that this PPC establishes a connection between the pericardial cavity and the peritoneal cavity, so this connection is between the peritoneal cavity and the space between the two layers of the pericardium and has no connection with the pericardial sac (the space where the heart is located). In this study, the anatomical structure and morphometry of the PPC in immature beluga were investigated, and some approaches were presented to observe the canal in ultrasonography.