Lymph Node, 40X
 
Lymphatic follicles or nodules (ln) are found in the cortex--outer layer--of lymph nodes. Follicles are spherical in shape, so they look circular in cross section. They often have lighter areas called germinal centers. Lymphatic follicles are also found in the spleen, tonsils, the wall of parts of the digestive tract (ileum, vermiform appendix) and the walls of the bronchi. The medulla (inner part) of a lymph node does not contain lymphatic follicles.

Lymph Node, 100X
 
This image shows part of the medulla of the lymph node in the image above. The cells in the medulla are arranged in medullary cords, which are thin, irregular-shaped inward extensions of the cortex. Between the medullary cords are medullary or lymph sinuses. Neither of these medullary structures is obvious in this image, but you can tell that you are not looking at the cortex because there are no lymphatic follicles in the image.

Lymph Node, 400X
 
This image shows the medulla of a lymph node. The large irregular blob in the lower left is a cross section of a trabecula--a branch of the capsule that extends inward to act like a skeleton for the lymph node.








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