Lymph node (fetus, human)

Stain: Trichrome (Goldner). Along the course of lymphatic vessels lymph nodes develop. Lymphatic vessels dilate and form lymphatic sacs and lymphocytes aggregate around these sacs. A tiny developing lymph node with dense-stained thymocyte nuclei is closely associated with dilated lymph capillaries. At this age no division of cortex and medulla is observed. Small penetrating arterioles filled with erythrocytes (orange) as well as few postcapillary venules (high endothelial venules, HEV, -->) are already present. Background: The cortex and medulla of these lymph nodes are not fully developed until a few weeks postnatally.