Drc7 is required for male fertility, head morphogenesis, and sperm flagellum formation.

(A) Drc7^+/- or Drc7^-/- males were mated with wild-type females and the number of pups born per plug is reported. Although 17 plugs were observed, Drc7^-/- male mice did not sire offspring. Error bars represent S.D. ***p < 0.001 (unpaired Student's t-test). (B) Testis morphology and (C) testis/body weight of Drc7^+/- and Drc7^-/- adult mice. Error bars represent S.D. *p < 0.05 (unpaired Student's t-test). Scale bar, 5 mm. (D) PAS staining of seminiferous tubules and cauda epididymis of adult mice. In stage VII-VIII, normal spermatocytes (red arrowhead) and round spermatids (white arrowhead) were observed in both Drc7^+/- and Drc7^-/- testis; however, elongated spermatids (black arrowhead) were hardly detected in Drc7^-/-. In stage IX, elongated spermatids were released in Drc7^+/- but they were retained in Drc7^-/- (red arrow). Stage XI step 11 spermatids of Drc7^+/- mice had normal, hook shaped heads (black arrow) whereas Drc7 KO step 11 spermatids have abnormal “club-shaped” heads (white arrow). In cauda epididymis, spermatozoa were hardly seen in Drc7^-/- mice. Scale bar, 50 μm. (E) Observation of spermatozoa extracted from cauda epididymis. Sperm mitochondria (midpiece) is stained with Mitotracker (red). Spermatozoa from Drc7^-/- mice have abnormal head shapes, short tails, disrupted midpieces, and are immotile. Hoechst (white), nucleus. Scale bar, 10 μm. (F) The measurement of sperm tail length. Drc7 KO spermatozoa exhibit shorter tails. ***p < 0.001 (unpaired Student's t-test).