Lymph nodes

Examine sections of lymph nodes on slides 30, 79 and 42 and note first the overall organization and the specific structures shown in Figs. 14-17 through 14-19. Identify

• The cortex,
• Paracortex,
• Medulla
• Subcapsular sinus (Fig. 14-19)
• The large clusters of cells, the lymphoid follicles with germinal centers (Fig. 14-18).
  • Various cells with different immune functions are located in these follicles.

Examine the specimen stained immunohistochemically in Fig. 14-20 and note the different localizations of T cells and B cells.

Did the cortex of the thymus show follicles of lymphocytes?

Clinical note: Lymphomas involve neoplastic growth of lymphocytes, commonly within lymph nodes. There are several types, depending on the type of lymphocyte and the stage of differentiation involved. In the early stage, lymphomas commonly involve cell accumulation caused by their failure to undergo apoptosis. Pictured here is a child with Burkitt's lymphoma.

The silver-stained specimen on slide 99 shows very well the reticular network and other supporting tissues, as well as the sinuses of the lymph node (Fig. 5-12b). Identify lymph.

• Can afferent or efferent lymphatics be identified in this section?

What are some of the unique staining characteristics of the stain used on slide 99?

A little more on the structure of lymph nodes.