Male Pseudohermaphroditism in the Bowhead Whale, Balaena mysticetus

Abstract

Examination of two bowhead whales, Balaena mysticetus, revealed an unusual assembly of reproductive structures. Although the external phenotype was female, the gonads were underdeveloped testes. In the more thoroughly studied of the two whales, all derivatives of the mesonephric (wolffian) and paramesonephric (müllerian) ducts were absent, and there was an apparently normal male karyotype (40 autosomes + XY). These findings suggest a failure of androgen expression consistent with the syndrome of complete testicular feminization reported in other species. Structural comparisons with two normal male bowheads confirm abnormal development in the two affected whales.