CCDC28A and microcephaly: Scanning electron microscopy further confirmed that the sperm from the Ccdc28a–/– mice showed obvious sperm head defects including bent heads, microcephaly, and irregular shapes (Fig. 2D, E), while the sperm flagellum from both Ccdc28a+/+ and Ccdc28a–/– mice had normal morphology (Fig. 2D, F).