Venn diagram analysis of sex-biased genes during middle age. The intersection of genes exhibiting sex-biased expression at middle age groups (8, 15, and 21 weeks) was calculated using Venn analysis. The genes commonly sex-biased (i.e., Venn intersection) were divided into female- and male-specific gene lists, and functional analyses using Ingenuity Pathway Analysis was performed. Middle age groups (8, 15, and 21 weeks) showed relatively equal numbers of sex-biased genes. Sex-biased gene lists were analyzed for over-represented gene pathways or networks.