Donor and Recipient Rat Strains Affect Full-Term Development of One-Cell Zygotes Cultured to Morulae/Blastocysts

Abstract

Abstract. The present study was conducted to examine the developmental potential to offspring of rat embryos cultured from 1-cell to morula/blastocyst stage. Pronuclear zygotes from Wistar × Wistar or (SD × DA) × Wistar strains were cultured in modified rat 1-cell embryo culture medium (mR1ECM) for 96 h in 5% CO2 in air at 37 C. The proportion of the 3-way cross hybrid zygotes developing into morula/blastocyst stage (74%) was higher than that of the Wistar zygotes (66%). Day-5 morulae/ blastocysts developed in vitro were transferred into Day-3 or -4 pseudopregnant recipients of Wistar or SD × DA strain. The transfer of cultured embryos resulted in the birth of offspring at 13-59%, while that of non-cultured control blastocysts showed birth rates of 35-65%. The best offspring rate of cultured embryos (59%) was obtained when the hybrid 1-cell zygotes were cultured in mR1ECM medium and transferred into the 2-days earlier uteri of SD × DA recipients. These results suggest that genetic background of recipients as well as donors is a possible factor affecting full-term development of rat morulae/blastocysts derived from 1-cell stage zygotes cultured in vitro. Key words: Embryo transfer, Hybrid, In vitro culture, mR1ECM, Rat zygotes (J. Reprod. Dev. 50: [191][192][193][194][195] 2004) chini and Bavister [1] reported that glucose and phosphate are responsible for the 2-cell block of hamster embryos cultured in 5% O 2 , 5% CO 2 , and 90% N2. Based on that observation, 1-cell stage zygotes of mice [2], rats [3][4][5], and cattle [6,7] were f o u n d t o b e c a p a b l e o f o v e r c o m i n g t h e i r developmental blocks and of developing into the blastocyst stage when cultured in phosphate-and glucose-free hamster embryo culture medium-1, HECM-1 [1]. As for rats, Miyoshi et al. [5] reported that 80% of 1-cell stage zygotes cultured in modified HECM-1 medium of lowered osmolarity, named as rat 1-cell embryo culture medium (R1ECM), developed into morulae and blastocysts after 96 h. The same group [8] also demonstrated that morulae and blastocysts produced by in vitro f e r t i l i z a t i o n i n 0 . 4 % B S A / 1 1 0 m M N a C ls u p p l e m e n t e d m o d i f i e d R 1 E C M m e d i u m (mR1ECM) and in vitro culture in 0.01% PVA/80 mM NaCl-supplemented modified R1ECM medium had developmental potential to full-term. But, the rate of offspring production from cultured 1-cell rat embryos was not high (13-28%) and more than half of the recipient rats failed to maintain pregnancy [8,9]. While cultured embryos from Wistar strain rats have been transferred into the 1-day younger uteri of recipient Wistar rats (as common protocol), the suitability of rat strains for embryo recipients as well as zygote donors, and of Accepted for publication: December 12, 2003 Correspondence: M. Hirabayashi (e-mail: mhirarin@nips.ac.jp) or S. Hochi KATO et al. 192 embryo-recipient synchronization is poorly understood in rat offspring production from cultured embryos.The present study was conducted to examine the full-term developmenta...

Strain Differences in Superovulatory Response, Embryo Development and Efficiency of Transgenic Rat Production

“…Our results showed that the percentage of two-cell embryos developed from zygotes was about 90%, independently of the rat strain used. Similar cleavage rates of zygotes were also described by other groups for outbred SD, Wistar and hybrid rats (Hirabayashi et al, 2001a;Kato et al, 2004a). In contrast, a lower competence of rat zygotes from inbred strains to develop in vitro to two-cell stage have been reported (Iannaccone et al, 2001).…”

“…The same can be deduced from the sporadic reports about embryo culture of outbred (Oh et al, 1998;Kato et al, 2004a;Jiang & Tsang, 2004) and inbred (Ouhibi et al, 1994;Iannaccone et al, 2001;Zhou et al, 2003) rat strains.…”

Superovulatory Response, Oocyte Spontaneous Activation, and Embryo Development in WMN/Nrs Inbred Rats

“…Researchers often encounter obstacles, such as OSA and poor fetus development of in vitro fertilized and developed embryos [16,17,20,36,45]. In addition, data regarding the application of these techniques to different strains is still limited [4,31].…”

Developmental Responses of 2-Cell Embryos to Oxygen Tension and Bovine Serum Albumin in Wistar Rats

“…The modified medium was named rat 1-cell embryo culture medium (R1ECM) [11]. However, embryo transfer (ET) of in vitro cultured blastocysts still results in limited success [3,5,11], indicating that culture conditions for rat preimplantation embryos remain suboptimal.…”