Light micrograph showing the limit between a germinal centre (left) and the mantle (right) of a lymphoid secondary follicle. Highlighted in the germinal centre are several centroblasts (some of them in mitosis), large clear macrophages and apoptotic cells (bottom centre). In the mantle there are many lymphocytes with small dark nuclei. 0.5 micrometre thick section of plastic embedded material stained with toluidine blue.