ABSTRACT
This study was conducted on the atrioventricular node [AVN] and atrioventricular bundle [AVB] of five four-month-old ovine fetuses. The histological structure of these components was studied by routine histological techniques and use of specific staining methods. The AVN was caudally located adjacent to the root of the aorta. It was almost spherical in shape and consisted of twisty cells. The node was mainly composed of [P] cells. There were not seen internodal pathways in the heart of four-month ovine fetus. The AVB was a direct continuation of the AVN and it passed through the fibrous ring toward the apex of the interventricular septum. At this place the right bundle branch [RBB] was ramified. The cells of the AVB were wider, shorter and lighter than normal myocardial cells. Some of the bundle cells have been changed to purkinje cells, whereas some others still did not represent typical characteristics of purkinje cells
Subject(s)
Animals , Atrioventricular Node/anatomy & histology , Fetus , Sheep , HistologyABSTRACT
To provide information about the anatomy and histology of the cardiac sinu-atrial node of rat. This information is needed in various fields of veterinary sciences, such as anatomy, histology, physiology, pathology and cardiology. Compare the anatomy and histology of the rat with the available data on the sinu-atrial node of human being and other animals.Four male rats. A piece consisted of the upper part of the interatrial septum along with the right cranial vena cava and a part of lateral wall of right atrium and right auricle was separated from each heart. The sinu-atrial node was studied by using routine anatomical and histological techniques. The sinu-atrial node of the rat was almost triangular in shape. The mean dimensions of the node were 225micro m in length, 83 micro m in width and 216 micro m in thickness. The cells of the node were organized into groups and chains of cells. In general, the color differences between the nodal cells and the ordinary myocardial fibers of the right atrium were very weak and there were no intercalated discs at intercellular connections. Also, the cells near the sinu-atrial node artery were organized around it.The anatomical location of the sinu-atrial node in the rat is similar to those of human being, dog, cattle, horse, camel, cat and goat. In the heart of rat there was a central artery. In this respect, it was resemble to those of human being, dog and camel. However, in gaot, sheep, rabbit, cat, cattle and guinea pig there is no central artery in the node. There was a little amount nerve fibers within the sinu-atrial node of rat. In this respect, it is similar to that of guinea pig. Whereas, in man, horse, dog, cat and goat the nerve fibers are aboundant within the node
ABSTRACT
The histological structure of the atrio-ventricular bundle [AVB] was studied in 6 adult male guinea pig. The AVB was a direct continuation of the atrio-ventricular node [AVN] where it passes obliquely through the right atrio-ventricular fibrous ring toward the apex of the interventricular septum. After ramifying the right bundle branch [RBB] from the AVB, the bundle continued as the left bundle branch [LBB] at the apex of interventricular septum. The LBB was broader than the RBB. Histologically, the cells of the AVB appeared to be organized into fascicles separated by fine fibrous septa. The majority of the cells of the AVB and bundle branches were ovoid in shape with light cytoplasm and a central nucleus. There was intercalated disc at their intercellular junctions. In general, compared to the conduction system of human being and other animal's heart, the innervation of the AVB and its branches in the heart of guinea pig was poor and there were no ganglia within or around them