In vitro culture of melanomacrophages from the spleen and liver of turtles: comments on melanomacrophage morphology.

Melanomacrophages were extracted and cultured from the spleen and liver of three turtle species representing three divergent families, the Chelydridae, Emydidae, and Trionychidae. Homogeneous cultures were obtained by repeatedly forcing minced, frequently washed tissue through a sterile screen and separating the resulting cells by centrifugation. The cells were surprisingly resistant to lysis and were maintained in culture for over 12 weeks where culture characteristics, appearance, and longevity from these two organs were similar. They attached to the T flask substrate as individual cells and aggregates and spread out 14 days after being placed in media. Ridges and ruffles at the distal ends of pseudopodia and the cell surface along with a zone of clearing attest to the cells' phagocytic nature. A few melanomacrophages from both organs underwent mitosis 14 days after treatment with granulocyte macrophage colony-stimulating factor but it is possible that other factors contributed to stimulation of cell division.