Figure 1: Microarray-generated miRNA expression profiles of testicular tissues from the NOA and control groups. (a) Hierarchical clustering of the miRNAs produced trees with significant differences between the patients with NOA and the control group. Rows: miRNAs; columns: samples. The legend at the top depicts how the relative miRNA expression levels are illustrated: blue indicates low expression, whereas yellow indicates high expression. (b) Volcano plot visualizing miRNA expression changes in the two groups. The vertical lines indicate fold changes of 2.0 and −2.0, respectively, and the horizontal line represents P = 0.05. (c) The scattered plot intuitively reflects the number of genes with significant differences. The genes labeled red are upregulated, those marked green are downregulated, and those labeled black are nonsignificant difference genes. The vertical coordinates are the logarithmic values of the corresponding samples. NOA: nonobstructive azoospermia; miRNAs: microRNAs.