The architecture of rat lymph nodes. II. Lymph node compartments.

Although lymph nodes are conventionally regarded as composed of superficial cortex, deep cortex, and medullary cords merge gradually into each other, the sinuses, the interstitium, and the germinal centres are separated by cellular borders that seem sufficiently complete to limit the rate of exchange of cells and molecules. Accordingly, the cellular composition shows distinct differences on either side of these borders. These compartments show further division into regions, the sinuses into superficial and deeply situated sinuses, the interstitium into superficial interstitium, follicles, paracortical nodules, and medullary interstitium, characterized by differences in densities of various cell types. Mechanisms behind the different distribution of cells within the different lymph node compartments and regions are discussed.