How long after being collected can blood still be cultured for chromosomal studies in the tropics.

To examine how long after their collection samples of peripheral blood could be successfully cultured for cytogenetic analysis in tropical countries, we determined the mitotic index in cultures of blood stored for up to 7 days in summer and winter. The results indicate that chromosomal analysis is successful if blood is stored for up to 2 days in summer or for up to 4 days in winter before initiating culture. Storing the blood in tissue culture medium rather than in heparin solution did not significantly improve the mitotic index.