DNA microarray analysis of gene expression in testis, ovaries, males, and females. Frequency histograms of hybridization fold intensity differences, from microarrays printed with testis cDNAs and hybridized with labeled cDNA from (A) testis versus male, (B) ovary versus gonadectomized female, (C) testis versus ovary, and (D) gonadectomized male versus gonadectomized female. The hybridization intensity difference (x-axis) is plotted against the frequency of microarray element falling within each class (y-axis). Where the tissue shown as the numerator resulted in stronger hybridization signal, the intensity difference has a positive value; where the tissue shown as the denominator resulted in a stronger hybridization signal, the intensity difference has a negative value. The broken line indicates where the 1:1 hybridization intensity (no difference) falls on the x-axis. The median intensity difference is given (arrow).
