Germline-soma Supply Mitochondria for mtDNA Inheritance in Mouse Oogenesis

Abstract Maternal transmission paradigm of mtDNA remains controversial in mammalian oogenesis. Germline-soma-to-oocyte communication by numerous transzonal nanotubes (TZTs) reminds whether intercellular mitochondrial transfer is associated with maternal inheritance. Here, we found that mouse oocytes egocentrically receive mitochondria via TZTs, which projected from germline-soma, to achieve 10 5 copies, instead of de novo synthesis of mtDNA subpopulation in growing oocytes. De novo assembled TZTs amongst germline-soma and oocytes accumulated mtDNA amounts of the oocytes in vitro . However, mitochondrial supplement from germline-soma gradually diminished along with oocyte growth and was terminated by meiosis resumption, in line with a decrease in the proportion of germline-soma with thriving mtDNA replication and FSH capture capability. Thus, germline-soma-to-oocyte mitochondrial transfer is responsible for mammalian mtDNA inheritance as well as oogenesis and aging. One-sentence summaries The maternal mtDNA transmission accompanied by oogenesis is inseparable from germline-soma mitochondrial transport.