From the observation of the origin of the 2 bp deletion of the ND2 mtDNA gene from the paternal germ line, it is thought that this mutation occurred in embryogenesis and therefore the paternal leakage of mtDNA is status occurs mainly during the early stages of fertilization and embryo development (Schwartz & Vissing 2002). Taking into account the theory of loss of paternal mtDNA during embryogenesis, it is necessary to study the process of embryogenesis. Embryogenesis is the formation and development of embryos in which, after the egg has been fertilized by sperm, mitochondria from the sperm enter the egg cell. Here in the egg is where the sperm mitochondria are outnumbered by the maternal mitochondria and are killed through a mechanism that identifies the ubiquitin with which the sperm are labeled. Therefore, paternal mitochondria are not transmitted to subsequent cellular stages of embryonic development and mtDNA is thought to have exclusively maternal inheritance. Taking into account the case study, the question that is raised is how paternal inheritance of mtDNA could have occurred if embryogenesis prevents it. Therefore, further research can be conducted on mtDNA recombination to see if mtDNA can be similar to nuclear DNA, where mtDNA can be incorporated or fused from many sources (Bromham et al 2002). Further investigating the paternal inheritance of mtDNA observed in other mammalian species besides humans, studies were conducted on interspecific crosses of two mouse species, Mus spretus and Mus musculus. Three elements were addressed that included whether leaked paternal mtDNA in fertilized eggs would show a stable distribution in all tissues when developed into adults, whether leaked paternal mtDNA would be passed on to subsequent generations, and… . half of the document ...... the presence of paternal mtDNA through allele-specific PCR (AS-PCR) tests. The results showed that 27 of the 4092 offspring contained paternal mtDNA, thus showing a paternal leakage rate of 0.66%. The experimental methods were divided into separate mating experiments (ME) in which ME1 DNA from 2046 offspring was isolated and screened for paternal inheritance via the AS-PCR1 technique. Six offspring from two separate matings contained losses of paternal mtDNA. Of the six offspring, one contained heteroplasmy and another had mtDNA turnover from maternal to paternal mtDNA. To confirm these results, a second screening of the offspring with AS-PCR2 was performed. For ME2, two mating pairs independent of each other presented mtDNA paternally. Two pairs of offspring were observed to contain heteroplasmy (Wolff et al 2013).