Circulating blood enters the bone through the central artery which branches out into small arterioles. These arterioles are interspersed in the cords of hematopoietic tissue. The arterioles drain into venous sinuses (space or cavity). Sinuses have a basement membrane which is lined by endothelial cells within the sinus and surrounded by reticular (e.g. adventitial) cells on other side. Blood from several venous sinuses may combine in a collecting sinus which leads to a central vein. The venous sinuses alternate with hematopoietic cords in a spokelike pattern with the central vein as the core.
