A nodule or mass resulting from displacement of tissue when atavism occurs in embryonic development; represents a reversion to structures not normally occurring in the individuals of a species, but observed in ancestral forms of that species.
[pro- + G. gonos, offspring, + -oma, tumor]
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Some similar morphologic characteristics between jawbone tumors in cattle and the infant neuroectodermal melanocytic progonoma are mentioned (WISEMAN et al.