Mitochondrial DNA is synthesized during meiosis and spermiogenesis in the mouse.

Following intratesticular injection of [3H]thymidine, spermatozoa were isolated from the caput and cauda epididymis of CD-1 mice. Quantitation of the amount of radiolabelled DNA in whole spermatozoa, sperm heads (nuclei) and sperm midpiece-tails (mitochondria) at time intervals 3-36 days postinjection demonstrated mitochondrial DNA (mtDNA) is synthesized during meiosis and early spermiogenesis. mtDNA synthesis terminates in mid-spermiogenesis suggesting that the mitochondrial genome in spermatozoa has a half-life of at least 15 days.