Anatomy and histology of the sinu-atrial node in the heart of guinea pig (Cavia percellus)

Abstract

Anatomy and histology of the sinu-atrial node was studied in 6 male guinea, pigs. The sinu-atrial node (0.14mm x 0.03mm x 0.55mm) lied beneath the epicardium, at the more caudal part of terminal sulcus, near the junction between the right cranial vena cava, lateral wall of the right atrium and. the right auricle. Its shape was like a trapezoid with curved sides. Its cranial end was near the right auricle and, it was wide, while the caudal end was near the myocardium of the atrial wall and it was narrow. Histologically, it contained very little collagen and the cell with clear perinuclear zone (P) were the principal cells of parenchyma. The transitional cell (T) was mainly located at the margins of the node. At the junction between the nodal cells intercalated discs were not seen. Most of the time, there were one or more arterioles at the cranial end of the node and in a few cases, there were arterioles at both the cranial and the caudal ends of the node that supply the node. © GSP, India.