The interior space enclosed by a tube such as a blood vessel. Grossly comprised of a capsule , cortex and medulla . Underlyingthe capsule is the subcapsulary sinus containing scattered reticular cells , macrophages ,circulating lymphocytes and a boundary of edothelial cells . Follicles lacking germinal centers are called primary, those with are called secondary. The medulla is composed of densely cellular medullary cords and less densely populated medullary sinuses .
Medullary sinuses are continuous with efferent lymphatic vessels found in the lymph node's hilum .
Small white blood cells containing little cytoplasm and compact nuclei. A large phagocytotic cell, not a leucocyte, often with slightly eosinophilic cytosplasm. Function primarily in engulfing cellular debris formed as a consequence of wounding, aging and infection. The multilobed nucleus often appears to be several independent nuclei, making discrimination of these cells from osteoclasts somewhat difficult. The cell cytoplasm is somewhat granular.