Light microscopy of a lymph node stained to show the connective reticular tissue. Reticular tissue is a type of collagen that forms an internal meshwork of fibres to support the blood vessels and the cells of the lymphoid system. Patches of dense tissues represent the lymphoid follicles containing immune cells such as lymphocytes. Lymph nodes receive lymph fluid from lymph vessels and will initiate an immune response if foreign material (micro-organisms, poisons/toxins, infectious agents) are detected. Magnification x50 when printed at 10 cm.