Lymphatics

• Lymphatic nodules - *always B cells (remembering that will help you with all of the secondary questions), primary (no germinal center, has not been antigenically challenged), secondary (germinal center*-has been antigenically challenged therefore it contains plasma cells and memory B cells*). They are found in the lymph node, palatine tonsil, ileum, colon, and appendix

• Lymph node - ID by the lymphatic nodules which are located all around the outside (cortex), also it has a capsule and a sub-capsular (not sub-scapular) sinus. If you remember that lymphatic nodules are only B cells, and the lymphatic nodules are located in the cortex, then the cortex has B cells! Next, paracortex has T cells and then the medulla has B cells! (BTB)

• Palatine tonsil - ID by the lymphatic nodules that are located everywhere (vs. in the periphery in the lymph node) also, it has crypts

• Thymus-no lymphatic nodules * (duh, it only has T cells!) Darker area outside is the cortex, lighter area inside is the medulla. **Hassel’s corpuscles-pink circular things, made of degenerating epithelial-reticular cells. If you look at it on high magnification you see lots of lymphocyte cells (black dots) and the occasional pink cells which are the epithelial-reticular cells

• Spleen - ID by the lymphatic nodules (white pulp but actually stains blue?????) with a central arteriole. Remember that the white pulp, since it is nothing more than a lymphatic nodule has B cells but, the area immediately around the central arteriole, PALS has T cells* Everything else in between is the red pulp

• Appendix - circular thing with a lumen and lymphatic nodules all around it. If you look closer, you will see that is has GI tract epithelium (simple columnar with goblet cells and a brush border)

Category: Anatomy Notes