However, Hsf5−/− males demonstrated infertility and markedly diminished testicular size relative to Hsf5+/+ and Hsf5+/− littermates (Figure 2D), with fertility tests confirming the infertility of Hsf5−/− males but the fertility of Hsf5−/− females (Figure 2E and Supplementary Figure S2I). Here, HSF5 is linked to Infertility.