Composition and Function of Haemolymphatic Tissues in the European Common Shrew

Bray, Daniel P.; Bennett, Malcolm; Stockley, Paula; Hurst, Jane L.; Kipar, Anja

Both in bone marrow and splenic red pulp, the degree of haematopoiesis was similar in animals from all age groups. This concurs with similar findings in the musk shrew [43] , where both the splenic red pulp and bone marrow have been identified as physiological sites of erythropoiesis, leukocytopoiesis and platelet production over the animal's lifespan. In this aspect, shrews are similar to some reptiles, whereas in other mammals the haematopoietic capacity of the spleen seems to cease after birth [43] . We also found evidence of haematopoiesis in the pancreas of Aselli in adult S. araneus, as demonstrated by the presence of megakaryocytes in the medulla of some individuals. Interestingly, we found no evidence of major thymic involution in S. araneus, even in older animals. The rate of thymic involution is known to vary between species and breeds and with intraspecific factors such as sex and diet [48, 49] . Perhaps in shrews thymic involution is delayed to maintain production of T cells into adulthood.