Selective labelling of lymphoid tissues by extracorporeal perfusion.

A method for selective labelling of lymphoid tissues by means of an extracorporeal perfusion system is described. The applicability of this technique was tested by local labelling of a part of the small intestine with its mesenteric lymph nodes, spleen and bone marrow in normal young pits. Tritiated thymidine was added to the perfusate and the selectivity of the labelling procedure tested by scintillation counting of serum samples, of specimens of lymphoid tissues and by autoradiography. There was only negligible spillover of the isotope and the perfused organs were well preserved.