GPX4 and Infertility: While homozygous total GPX4 deletion is lethal in embryo, spermatocyte-specific GPX4 knock-out mice are infertile, with decreased number of spermatogenic cells in seminiferous tubules and spermatozoa in epididymis, reduced spermatozoa motility (absence of forward motility), reduced mitochondrial membrane potential, mitochondrial swelling, and midpiece morphological changes with tail bending in a hairpin form, similarly as in the severe Se deficiency (104–107).