This micrograph is a high magnification of the area in the rectangle of the previous micrograph. The venous sinus in the center of the micrograph has been cut in cross section. Other than the lysed red blood cells, which appear as empty circular profiles, a number of lymphocytes (Ly) are present in the lumen. The wall of the sinus as seen here consists of rod-like endothelial cells (EC) that have been cut in cross section. A narrow, but clearly visible intercellular space is present between adjacent cells. These spaces allow blood cells to pass readily into and out of the sinuses. Also, processes of macrophages located outside of the sinuses in the splenic cords extend between the endothelial cells and into the lumen of the sinuses to monitor the passing blood for foreign antigens. The endothelial cell nuclei (ECN) project into the lumen of the vessel and appear to be sitting on top of the cell. A macrophage (M), identified by residual bodies in its cytoplasm, is seen just outside of the sinus.
Spleen, human, silver preparation, ×128.
This micrograph shows a splenic nodule (SN) occupying the upper portion of the micrograph and below red pulp (RP). The components that can be identified are a germinal center (GC), a central artery (CA), and venus sinuses (VS) in the red pulp.
The structural elements that are stained by the silver in the nodule consist of reticular fibers. Note their paucity within the germinal center. The fine, thread-like stained material that encircles the venous sinuses is a usual modification of basement membrane.
Venous sinuses, spleen, human, silver preparation, vessel has been cut deeper along its long axis, the basement membrane ap×515. pears as dot-like structures (arrowheads). A three-dimensional reconstruc tion of the basement membrane would reveal it as a series of ring-like This micrograph reveals several venous sinuses (VS). Where structures.
the vessel wall has been tangentially sectioned the basement membrane appears as a ladder-like structure (BM). Where the
KEY BM, basement membrane CA, central artery EC, rod-like endothelial cells ECN, endothelial cell nuclei GC, germinal center Ly, lymphocytes M, macrophage RP, red pulp SC, splentic cords SN, splenic nodule TV, trabecular vein VS, venous sinuses VW, venous sinus wall