Nice open circulation flow! For comparison, write out the steps for closed circulation below.

Elongated epithelial cells line the walls of splenic sinusoids in the slide above (Slide 73, Spleen, Kornhauser’s Quad). These cells are oriented in the direction of blood flow, have few contact points, and a discontinuous basal lamina producing spaces between the cells. These spaces allow functional blood cells to reenter the vasculature while surrounding macrophages engulf old or damaged cells.

These elongated, fusiform-shaped endothelial cells of the splenic sinusoids are known as:

The spleen is considered a ____ lymphoid organ.