Sinoatrial nodal artery variant in approximately 10% of human hearts. This artery is larger than normal and supplies a good part of the left atrium, but also right sided structures like part of the sinoatrial node and the atrioventricular nodal areas. In this variant, the artery courses in the sulcus between the left superior pulmonary vein and the left atrial appendage where it could be susceptible to injury during catheter or surgical ablation procedures on the left atrium, especially for atrial fibrillation ablation or open heart cardiac surgery. Sinoatrial nodal artery The sinoatrial nodal artery (or sinuatrial nodal artery or sinoatrial artery) is
Lymph node stromal cell the "T cell zone". B lymphocytes (cells which help to fight certain bacteria) are located in the "B cell follicle". The primary B cell follicle matures in germinal centers. In the medulla are hematopoietic cells (which contribute to the formation of the blood) and stromal cells. Near the medulla is the hilum of lymph node. This is the place where blood vessels enter and leave the lymph node and lymphatic vessels leave the lymph node. Lymph vessels entering the node do so along the perimeter (outer surface). The lymph nodes, the spleen and Peyer's patches, are known as secondary lymphoid