DEVELOPMENT OF THE LYMPHOID-TISSUES OF THE TAMMAR WALLABY MACROPUS-EUGENII

A study has been made of the development of four lymphoid tissues from birth to maturity in the tammar wallaby Macropus eugenii--the cervica l and thoracic thymus, lymph nodes and gut-associated lymphoid tissue (GALT). The development of these tissues in the tammar wallaby is simi lar to that in two other marsupials, the quokka Setonix brachyurus and the Virginian opossum Didelphis virginiana. Lymphocytes were first de tected in the cervical thymus of the tammar at Day 2 post partum and i n the thoracic thymus at Day 6. They were subsequently detected in lym ph nodes at Day 4 and in the spleen by Day 12 but were not apparent in the GALT until around Day 90 post partum. By Day 21, the cervical thy mus had developed distinct areas of cortex and medulla and Hassall's c orpuscles were apparent. The maturation of other tissues followed with Hassall's corpuscles in the thoracic thymus by Day 30 and nodules and germinal centres in the lymph nodes by Day 90. Measurement of immunog lobulin G concentrations in the serum of young animals indicated a ris e in titre around Day 90 post partum, correlating with the apparent ma turation of the lymphoid tissues.