title: Testicular oocytes in MRL/MpJ mice possess similar morphological, genetic, and functional characteristics to ovarian oocytes.
abstract: In general, mammalian males produce only spermatozoa in their testes and females produce only oocytes in their ovaries. However, newborn MRL/MpJ male mice produce oocytes within their testes. In this study, we examined the initiation and progression of oogenesis in fetal and neonatal MRL/MpJ mouse testes and evaluated the characteristics of testicular oocytes. Germ cells with positive reactions to oogenesis markers such as NOBOX oogenesis homeobox and synaptonemal complex protein 3 were observed in the MRL/MpJ fetal testes on embryonic day 18.5. These fetal testicular oocytes possessed maternal-specific methylation patterns of histone and DNA. The level of DNA methylation was still low in postnatal testicular oocytes at day 14 after birth. Additionally, the postnatal testicular oocytes contained both X and Y chromosomes and had the ability to fuse with sperm. These results suggest that some XY germ cells in fetal testes of MRL/MpJ mice enter meiosis prematurely, undergo oogenesis, and differentiate into oocytes. In addition, MRL/MpJ testicular oocytes have the ability to carry on oogenesis before and shortly after birth until they obtain some of the morphological, epigenetic, and functional characteristics of oocytes.
authors.affiliation: Laboratory of Anatomy, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan. Electronic address: saori-o@vetmed.hokudai.ac.jp.
authors.forename: Saori
authors.initials: S
authors.lastname: Otsuka-Kanazawa
authors.affiliation: Laboratory of Anatomy, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Ichii
authors.affiliation: Laboratory of Anatomy, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Kon
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D018797:Cell Cycle Proteins; D019175:DNA Methylation / Q000235:genetics / Q000502:physiology; D004268:DNA-Binding Proteins; D044127:Epigenesis, Genetic / Q000235:genetics / Q000502:physiology; D005260:Female; D005801:Genes, Homeobox / Q000235:genetics; D018398:Homeodomain Proteins / Q000235:genetics; D008297:Male; D008540:Meiosis / Q000235:genetics / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D009687:Nuclear Proteins / Q000235:genetics; D009865:Oocytes / Q000378:metabolism / Q000502:physiology*; D009866:Oogenesis / Q000235:genetics / Q000502:physiology*; D010053:Ovary / Q000378:metabolism / Q000502:physiology*; D012730:Sex Chromosomes / Q000235:genetics; D013094:Spermatozoa / Q000378:metabolism / Q000502:physiology; D013737:Testis / Q000378:metabolism / Q000502:physiology*; D014157:Transcription Factors / Q000235:genetics
chemical_list: D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D018398:Homeodomain Proteins; D009687:Nuclear Proteins; C456265:Og2x protein, mouse; C490062:Sycp3 protein, mouse; D014157:Transcription Factors
keywords: DNA methylation; H3K9me2; MRL/MpJ mouse; Meiosis; Oogenesis; Testicular oocytes