HSF5 is essential for meiosis in the male germline. (A) Schematic of the generation of Hsf5 knock out mice with CRISPR-Cas9 genome editing system. (B) Western blotting analysis of the HSF5 protein expression in testes extracts from wild type and Hsf5−/− testes at P56. β-actin is serve as loading control. (C) Comparison of body weight between wild-type and Hsf5−/−. Data are presented as mean ± SD, p < 0.05, n = 6. (D) Analysis of the litter size of heterozygous mice after mating. (E) Litter size of 8-week-old wild type and Hsf5−/− male mice. Data are presented as mean ± SD, p < 0.05, n = 6. (F) Gross morphology of the testis and the epididymis from wild type and Hsf5−/− mice at the age of 8 weeks. (G) Testis weight of 8-week-old wild type and Hsf5−/− male mice. Data are presented as mean ± SD, p < 0.05, n = 6.