| lutheran blood-group system | A complex blood group system having pairs of alternate antigens and amorphic genes, but also subject to a dominant independently segregating repressor. (12 Dec 1998) |
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| lymphatic system | <anatomy> The tissues and organs (including the bone marrow, spleen, thymus and lymph nodes) that produce and store cells that fight infection and the network of vessels that carry lymph. (12 May 1997) |