Quantitative parameters of melanomas differentiation.

Melanin concentration which represents one of biochemical parameters expressing the degree of pigment cell differentiation was studied by new gravimetric procedure in human, Bomirski hamster, Harding-Passey mouse and horse melanomas and also in several non-tumor pigment tissues. In amelanotic varieties of human and hamster melanomas relatively high melanin level was discovered. This finding (together with known electron microscopic evidence of pre-melanosomes presence in some amelanotic melanomas) suggests that the term "amelanotic" is not correct. Comparison of melanin content between melanomas and normal pigment tissues clearly demonstrates in quantitative way that as for melanomas their proliferation does not decrease the degree of their biochemical differentiation.