A Histological Investigation of the Lymphoid and Immunohaematopoietic Tissues of the Adult Stripe-Faced Dunnart (Sminthopsis macroura)

Abstract

This is the first published description of the lymphoid and immunohaematopoietic tissues of an Australian polyprotodont, the stripe-faced dunnart, Sminthopsis macroura and the first account of bronchus-associated lymphoid tissue (BALT) in a metatherian. Histologically, the tissue beds are similar in appearance to those reported in other adult eutherian and metatherian mammals. The liver and bone marrow were mature and virtually no haematopoietic activity was observed. The thymus had undergone involution but retained some lymphocytes. The spleen was similar to that observed in other metatherians containing areas of red and white pulp separated by a marginal zone. Lymph nodes, except for a pair in the posterior abdomen, were difficult to locate but were similar to those observed previously in other adult metatherians. Peyer’s patches were present; however, they lacked dome regions and sometimes had villi above them. BALT appeared to be both compartmentalised and non-compartmentalised in the adult stripe-faced dunnart.