PANCREAS OF ASELLI IN SOME SPECIES OF THE SHREWS (SOREX-ARANEUS AND NEOMYS FODIENS) AS AN ANALOG OF THE BURSA OF FABRICIUS IN BIRDS

No organ equivalent to the bursa of Fabricius in birds, which is respo nsible for the production of B cells, has been found in mammals thus f ar. It has been suggested that Peyer's patches and the appendix along with the bone marrow play this role. In this study, the gland of Asell i of shrews was examined, whose function has not yet been clarified. T he results of the study of the gland of Aselli in common and water shr ews suggest this gland to be the key lymphoid organ analogous to the b ursa of Fabricius. However, unlike the bursa of Fabricius, the gland o f Aselli seems to fulfil two functions. It not only produces B cells, but also is the site of their terminal differentiation into plasma cel ls. (C) 1997 Academic Press Limited.