Heteromorphic sex chromosomes in male rainbow trout

Science  20 May 1977:
Vol. 196, Issue 4292, pp. 900-902
DOI: 10.1126/science.860122


A pair of subtelocentric chromosomes differs in the size of the short arm in male, but not female, rainbow trout (Salmo gairdneri). The morphological similarity of the X and Y chromosomes, and the observation of Y chromosomes intermediate between the X and normal Y, suggest that the sex chromosomes are at an early stage of differentiation in this species.