Potential testis-specific genes as revealed by tissue-profiling analysis. Genes were selected on the basis of their high expression (average signal intensity ≥3rd quartile) in at least one testicular sample and low or null expression (average signal intensity < median) in 5 non-testicular tissues (Ovary, Liver, Muscle, Gill, and brain). Genes are displayed according to 3 broad expression clusters (i.e. somatic, spermatogonia and meiotic/post-meiotic). Roman numerals (I-VIII) indicate trout developmental stages. Sg = spermatogonia; Sc = spermatocytes; St = spermatids. Log-2 transformed signal intensities are shown according to the scale bar.