Crystal cell pattern modification in a melanotic tumor strain of Drosophila melanogaster.

3rd instar larvae of the melanotic tumor tu-pb strain of Drosophila melanogaster hold a lower number of free-circulating crystal cells in their hemolymph than the wild type ones. This pattern could result from an abnormal retention of mature crystal cells in the hematopoietic organs, as the strong hemocyte melanization inside the lymph glands of heat-treated tu-pb larvae seems to demonstrate. Melanotic tumor formation and modification of the crystal cell pattern may be related.