Description: The HIS51 monoclonal antibody reacts with rat CD90 and cross-reacts with mouse CD90.1, a GPI-linked membrane molecule. In the rat, CD90 is expressed by hematopoietic stem cells, immature B cells, thymocytes, recent thymic emigrants, neurons, inflammed endothelia and other cell types. In the CD90.1-expressing mouse strains, PL and AKR, CD90 is expressed by early hematopoietic cells in the bone marrow, thymocytes and mature T cells.