Editing Germ cell (section)

===Mutation and DNA repair===

The mutation frequencies for cells throughout the different stages of [[spermatogenesis]] in mice is similar to that in female germline cells, that is  5 to 10-fold lower than the mutation frequency in somatic cells<ref name="pmid9707592">{{cite journal | vauthors = Walter CA, Intano GW, McCarrey JR, McMahan CA, Walter RB | title = Mutation frequency declines during spermatogenesis in young mice but increases in old mice | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 95 | issue = 17 | pages = 10015–10019 | date = August 1998 | pmid = 9707592 | pmc = 21453 | doi = 10.1073/pnas.95.17.10015 | doi-access = free | bibcode = 1998PNAS...9510015W }}</ref><ref name="pmid23153565" />  Thus low mutation frequency is a feature of germline cells in both sexes. 
Homologous recombinational repair of double-strand breaks occurs in mouse during sequential stages of spermatogenesis, but is most prominent in [[spermatocyte]]s.<ref name="pmid9778439"/> The lower frequencies of mutation in germ cells compared to somatic cells appears to be due to more efficient removal of DNA damages by repair processes including homologous recombination repair during meiosis.<ref>Bernstein H, Byerly HC, Hopf FA, Michod RE. Genetic damage, mutation, and the evolution of sex. Science. 1985 Sep 20;229(4719):1277-81. doi: 10.1126/science.3898363. PMID 3898363</ref>  Mutation frequency during spermatogenesis increases with age.<ref name="pmid9707592" />  The mutations in spermatogenic cells of old mice include an increased prevalence of [[transversion]] mutations compared to young and middle-aged mice.<ref name="pmid15084311">{{cite journal | vauthors = Walter CA, Intano GW, McMahan CA, Kelner K, McCarrey JR, Walter RB | title = Mutation spectral changes in spermatogenic cells obtained from old mice | journal = DNA Repair | volume = 3 | issue = 5 | pages = 495–504 | date = May 2004 | pmid = 15084311 | doi = 10.1016/j.dnarep.2004.01.005 }}</ref>