Diaw Mouhamadou, Salgado Renato M, Canesin Heloísa S, Gridley Nell, Hinrichs Katrin
Department of Clinical Sciences, Faculty of Veterinary Medicine, University of Montreal, QC, Canada.
Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, 77843, TX, USA.
Theriogenology. 2018 Apr 15;111:62-68. doi: 10.1016/j.theriogenology.2017.12.044. Epub 2018 Feb 2.
Intracytoplasmic sperm injection (ICSI) is an important tool for equine embryo production in both clinical and research settings. In clinical ICSI programs, immature equine cumulus-oocyte complexes (COCs) are often collected at the mare's location and shipped to the ICSI laboratory. To simplify shipment and aid scheduling of subsequent procedures, COCs can be held overnight at room temperature (∼22 °C) before placement into maturation culture, with no detrimental effect on meiotic or developmental competence. A recent study indicated that it might be possible to hold COCs overnight at cold (∼4 °C) temperatures. If so, this might allow longer holding periods that would ease shipping requirements. In this study, we compared oocyte maturation rates, as well as cleavage and blastocyst rates after ICSI, for COCs held at either room or cold temperatures overnight before the onset of in vitro maturation. In Exp. 1, COCs were shipped overnight in a commercial embryo holding medium, ViGRO (Vg), in insulated containers designed to hold at either room temperature (RT, ∼22 °C) or cold temperatures (Cold, ∼7 °C). Subsequent rates of in vitro maturation, cleavage and blastocyst formation were significantly higher in the RT treatment (39%, 90% and 41%, respectively) than in the Cold treatment (23%, 60% and 17%, respectively, P < .05). In Exp. 2, we compared Vg medium with a second commercial embryo holding medium, SYNGRO (Sy). There was no significant difference between Vg and Sy groups in any evaluated parameter within either RT or Cold treatments. Within each medium group and for both media combined, the rates of in vitro maturation, cleavage and blastocyst formation were significantly higher in the RT treatment (42%, 81% and 42%, respectively for the combined media) than in the Cold treatment (29%, 54% and 10%, respectively for the combined media, P < .05). We conclude that shipment of immature equine COCs at cold temperatures (∼7 °C) is detrimental to subsequent in vitro maturation and embryo production.
胞浆内单精子注射（ICSI）在临床和研究环境中都是马胚胎生产的重要工具。在临床ICSI项目中，未成熟的马卵丘-卵母细胞复合体（COCs）通常在母马所在地采集，然后运送到ICSI实验室。为了简化运输并便于安排后续程序，COCs在放入成熟培养液之前可以在室温（约22°C）下过夜保存，这对减数分裂或发育能力没有不利影响。最近的一项研究表明，COCs可能可以在低温（约4°C）下过夜保存。如果是这样，这可能允许更长的保存时间，从而缓解运输要求。在本研究中，我们比较了在体外成熟开始前在室温或低温下过夜保存的COCs的卵母细胞成熟率，以及ICSI后的卵裂率和囊胚率。在实验1中，COCs在商业胚胎保存培养液ViGRO（Vg）中过夜运输，置于设计为可保持在室温（RT，约22°C）或低温（Cold，约7°C）的保温容器中。RT处理组的体外成熟、卵裂和囊胚形成的后续发生率（分别为39%、90%和41%）显著高于Cold处理组（分别为23%、60%和17%，P<0.05）。在实验2中，我们将Vg培养液与第二种商业胚胎保存培养液SYNGRO（Sy）进行了比较。在RT或Cold处理中的任何评估参数上，Vg组和Sy组之间均无显著差异。在每个培养液组内以及两种培养液合并后，RT处理组的体外成熟、卵裂和囊胚形成率（合并培养液分别为42%、81%和42%）显著高于Cold处理组（合并培养液分别为29%、54%和10%，P<0.05）。我们得出结论，未成熟马COCs在低温（约7°C）下运输对随后的体外成熟和胚胎生产有害。
