Lymph node composition is similar in all age groups, with a relatively high proportion of plasma cells, particularly in adults Mesenteric or mediastinal lymph nodes were examined from selected sub-adult and adult animals. All features normally associated with mammalian lymph nodes were represented: a cortex containing primary and secondary follicles, paracortex, lymphatic cords, medulla and both marginal and medullary sinuses. Compared to lymph nodes in other mammalian species [39, 42] , the medulla often appeared to contain a high number of plasma cells, particularly in adults. No other differences were observed between the age groups.