Composition and Function of Haemolymphatic Tissues in the European Common Shrew

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

Thymic tissue was recovered from seven animals across all age groups. This generally consisted of a variable number of lymphocyte layers which were arranged around blood vessels and encased by a thin capsule of fibrous connective tissue. Taking the histological features of a mouse thymus in account, the thymus appeared to exhibit a variable, but generally low degree of involution in all examined shrews, regardless of age. The bone marrow generally exhibits moderate to high activity, regardless of age The bone marrow generally exhibited moderate to high activity. All haematopoietic cell types known from other mammalian species were present. Approximately 10% of cells were identified as T cells, 10% as B cells (CD79a-positive, CD45R-negative; interpreted as circulating mature B cells) and 30% to 50% were myeloid/histiocyte antigen-and/or lysozyme-positive cells. At least 30% to 40% of all cells were PCNA-positive, representing relatively high levels of proliferation. No difference in bone marrow activity was found between sub-adult (n = 15) and adult (n = 16) shrews (Wald = 1.91, ns) or between males (n = 12) and females (n = 19; Wald = 0.74, ns).