Lampreys give clues to evolution of immune system

[Harlequinmania]

Biologists have discovered that primitive, predatory lampreys have structures within their gills that play the same role as the thymus, the organ where immune cells called T cells develop in mammals, birds and fish. The finding suggests that in vertebrate evolution, having two separate organs for immune cell development -- the bone marrow for B cells and the thymus for T cells -- may have preceded the appearance of the particular features that mark those cells, such as antibodies and T cell receptors.

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