Tissue culture study on Mongolian gerbil's (Meriones unguiculatus) malignant melanoma

We tried to culture melanoma cells from a Mongolian gerbil's (Meriones unguiculatus) malignant tumor. In primary culture, most of cells have abundant melanin granules in their cytoplasm. Melanin granules decreased through 5 to 15 serial passages and disappeared after 15 th passage. The morphology of the cells varied from spindle to large polydendritic cells. Although typical melanin granules were not seen when the cells were stained by Masson-Fontana method, the cells were positive for DOPA reaction. Electron microscopically, most of the cells have well-developed Golgi apparatus and rough-surfaced endoplasmic reticulum with dilated cistern, and premelanosome-like granules were frequently observed in their cytoplasm.