title: Optimized Protocols for In Vitro Maturation of Rat Oocytes Dramatically Improve Their Developmental Competence to a Level Similar to That of Ovulated Oocytes.
abstract: The developmental capacity of in vitro-matured (IVM) oocytes is markedly lower than that of their in vivo-matured (IVO) counterparts, suggesting the need for optimization of IVM protocols in different species. There are few studies on IVM of rat oocytes, and there are even fewer attempts to improve ooplasmic maturation compared to those reported in other species. Furthermore, rat oocytes are well known to undergo spontaneous activation (SA) after leaving the oviduct; however, whether IVM rat oocytes have lower SA rates than IVO oocytes and can potentially be used for nuclear transfer is unknown. In this study, we investigated the effects of maturation protocols on cytoplasmic maturation of IVM rat oocytes and observed the possibility to reduce SA by using IVM rat oocytes. Ooplasmic maturation was assessed using multiple markers, including pre- and postimplantation development, meiotic progression, CG redistribution, redox state, and the expression of developmental potential- and apoptosis-related genes. The results showed that the best protocol consisting of modified Tissue Culture Medium-199 (TCM-199) supplemented with cysteamine/cystine and the cumulus cell monolayer dramatically improved the developmental competence of rat oocytes and supported both pre- and postimplantation development and other ooplasmic maturation makers to levels similar to that observed in ovulated oocytes. Rates of SA were significantly lower in IVM oocytes than in IVO oocytes when observed at the same intervals after nuclear maturation. In conclusion, we have optimized protocols for IVM of rat oocytes that sustain ooplasmic maturation to a level similar to ovulated oocytes. The results suggest that IVM rat oocytes might be used to reduce SA for rat cloning.
authors.affiliation: 1 College of Animal Science and Veterinary Medicine, Shandong Agricultural University , Tai-an City, P. R. China . Post code: 271018.|2 These authors contributed equally to this work.|3 Present address: Reproductive Medicine Centre, Affiliated Hospital of Qingdao Medical University , Yuhuangding Hospital of Yantai, Yantai, Shandong, China . Post code: 264000.
authors.forename: Guang-Zhong
authors.initials: GZ
authors.lastname: Jiao
authors.affiliation: 1 College of Animal Science and Veterinary Medicine, Shandong Agricultural University , Tai-an City, P. R. China . Post code: 271018.|2 These authors contributed equally to this work.
authors.forename: Wei
authors.initials: W
authors.lastname: Cui
authors.affiliation: 1 College of Animal Science and Veterinary Medicine, Shandong Agricultural University , Tai-an City, P. R. China . Post code: 271018.
authors.forename: Rui
authors.initials: R
authors.lastname: Yang
authors.affiliation: 1 College of Animal Science and Veterinary Medicine, Shandong Agricultural University , Tai-an City, P. R. China . Post code: 271018.
authors.forename: Juan
authors.initials: J
authors.lastname: Lin
authors.affiliation: 1 College of Animal Science and Veterinary Medicine, Shandong Agricultural University , Tai-an City, P. R. China . Post code: 271018.
authors.forename: Shuai
authors.initials: S
authors.lastname: Gong
authors.affiliation: 1 College of Animal Science and Veterinary Medicine, Shandong Agricultural University , Tai-an City, P. R. China . Post code: 271018.
authors.forename: Hua-Yu
authors.initials: HY
authors.lastname: Lian
authors.affiliation: 1 College of Animal Science and Veterinary Medicine, Shandong Agricultural University , Tai-an City, P. R. China . Post code: 271018.
authors.forename: Ming-Ju
authors.initials: MJ
authors.lastname: Sun
authors.affiliation: 1 College of Animal Science and Veterinary Medicine, Shandong Agricultural University , Tai-an City, P. R. China . Post code: 271018.
authors.forename: Jing-He
authors.initials: JH
authors.lastname: Tan
mesh_terms: D000818:Animals; D002138:Calibration; D002478:Cells, Cultured; D047108:Embryonic Development; D005260:Female; D005307:Fertilization in Vitro; D059471:In Vitro Oocyte Maturation Techniques / Q000379:methods* / Q000592:standards; D009865:Oocytes / Q000166:cytology* / Q000502:physiology*; D010060:Ovulation / Q000502:physiology*; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley