Objectives To evaluate the usefulness of first-trimester crown−rump length (CRL)

Werdelin, 0. Demonstration of delayed-type hypersensitivity in guinea-pigs by the agarose plate technique. Acta path. microbiol. scand. Sect. C, 83: 52-58, 1975. A recently developed method for demonstration of antigen-dependant migration inhibition, the agarose plate technique, and skin tests were used to demonstrate delayed hypersensitivity towards Mycobacterium tuberculosis and Nocardia farcinica in guinea-pigs. Peritoneal exudate cells from animals immunized with M . tuberculosis and N . farcinica displayed immunologically specific inhibition of migration after stimulation with tuberculin and N. farcinica sensitin, respectively. T h e slight cross reactivity between the two antigens demonstrated by skin tests was also observed with the agarose technique. Previous skin testing did not influence migration inhibition of peritoneal exudate cells. Migration inhibitory activity of supernatants of tuberculin stimulated lymph node cells from guinea-pigs which had been immunized with M . tuberculosis was demonstrated on peritoneal exudate cells from non-immunized animals.

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