AbstractBACKGROUND: Beluga (Huso huso) is one of the sturgeons and currently is cultured artificially in Iran with different goals. The cardiovascular system is one of the important systems of the body, and heart is the most important organ in this system. So far, few studies have been done on the heart of sturgeons.OBJECTIVES: This study was done to determine the exact structure of beluga different parts of the heart septum using echocardiographic and histologic techniques. METHODS: Six immature male belugas (2.5 years old) were investigated in this study. For echocardiography, probe was placed on the ventral surface of body, between pectoral fins. At first, macroscopic morphologic studies of different parts of heart were done at the topographic place of them. For histological studies, usual methods of fixation and hematoxylin and eosin (H&E) coloring were used. Prepared slides were studied by light microscope.RESULTS: All parts of the heart including the sinus venosus, atrium, ventricle, conus arteriosus and pericardium were clearly visible in different probe moves. The pericardium were covered surround heart`s structures having homogenous echo pattern. Sinus venosus had a very thin septum without any expansion and contraction. Atrium had a completed muscular septum with expansion and contraction. Ventricle muscular septum had two layers: an external compact layer and an internal spongy layer. Conus arteriosus was composed of obvious muscular septum and connective tissue. Histological studies showed three layers in beluga heart including epicardium, myocardium and endocardium. In overall, the histological findings were matched with the results of echocardiography. CONCLUSIONS: This study is the first investigation on echocardiographic feature of different parts of beluga heart. These results were coordinated with histological findings. Normal information and findings of this study can be used for investigation of various anatomic or pathologic changes in beluga heart in different research projects.

BACKGROUND: The Eustachian tube is an osteocartilaginous channel connecting the tympanic cavity with the nasopharynx. There is no anatomical and histological research performed on this organ in buffalo. OBJECTIVES: Anatomical and histological study of Eustachian tube in buffalo will be useful for basic knowledge of this organ. METHODS: For this study 8 adult male and female buffalo's head were provided from slaughter house and their Eustachian tube were studied anatomically, then tissue samples were obtained and paraffin sections were prepared for using of staining methods such as H&E (for general study), Verhoff (for elastic fibers), PAS (for carbohydrates) and Masson's Trichrome Stainning Kit (for collagen fibers). RESULTS: Anatomical results showed Eustachian tube was white and funnel- like tube, no curve and structurally supported by cartilage and in both sexes they had the same structure. Histological and Histochemical results showed the epithelium of Eustachian tube in buffalo is pseudostratified ciliated columnar and in some regions of the Eustachian tube epithelium was stratified squamous. In the first portion of Eustachian tube cartilage was elastic and then eustachian tube cartilage was hyaline. The glands of Eustachian tube in buffalo were mucous and non folicular tubal tonsil could be found around the pharyngeal opening with obviously lymphoid tissue. CONCLUSIONS:. The results of this research can be used as the basic anatomical and Histological knowledge in buffalo..