The leukocyte culture method in the diagnosis of freemartinism.

The clinical application and reliability of the leukocyte culture method for the diagnosis of freemartinism were examined and the length of time that blood samples could be held at room temperature and in the refrigerator prior to culturing, was investigated. The chromosome findings by the leukocyte culture method in 14 freemartins and 9 non-freemartin females belonging to heterosexual twins or triplets revealed that XX-XY cell chimerism exists only in the former, whereas the latter were exclusively of normal female complement. The mitotic index in bovine blood after preservation for varying periods was studied on samples from two animals. Blood samples from these two animals stored at 5 degrees C for 6 hours in a refrigerator showed the mitotic index to be 3.8 and 5.3 per cent which gradually decreased in samples stored for longer than 12 hours. After 72 hours, a very rapid decrease in mitotic index occurred in both cases, reaching zero in samples stored for 96 and 108 hours. Samples kept at room temperature followed a similar pattern as under refrigeration but with slightly lower values throughout.