母豚の卵管と子宮の間の温度勾配を模倣することで、体外胚培養の生産性が向上します

Mimicking the temperature gradient between the sow's oviduct and uterus improves in-vitro embryo culture output.

• S García-Martínez
• R Latorre
• M A Sánchez-Hurtado
• F M Sánchez-Margallo
• N Bernabò
• R Romar
• O López-Albors
• P Coy

抄録

この研究は、雌豚の生殖管内の温度条件を決定し、生殖補助技術への影響を研究することを目的としています。体温は、腹腔内視鏡を用いた単一部位の手術を補助するアプローチと小型化されたプローブを使用して記録されました。母豚と雌豚は、それぞれ自然周期と卵巣刺激治療に対処するために使用されました。インビボ値に従って、インビトロ受精を3つの温度条件（37.0℃、38.5℃、39.5℃）で実施し、推定接合体をこれらの条件で20時間培養し、さらに胚培養（受精後21～168時間）を38.5℃に維持した。20時間後、異なる受胎可能性パラメータを評価した。胚培養中に開裂と胚盤胞の段階を評価した。実験温度における精子膜の流動性を、示差走査熱量測定法とフォトブリーチング後の蛍光回収法を用いて研究した。母豚の卵管と子宮の間には1.5℃の温度勾配の増加が認められ（p＜0.05）、この勾配を豚の体外培養に移行させると、体外受精後の多核接合体の数が減少し、胚盤胞の割合が増加した。さらに、イノシシの精子膜の温度転移期（37.0℃）は、雌豚卵管の温度と一致し、37.0℃では、より高い温度（38.5℃、39.5℃）で培養した精子と比較して、精子膜がより流動的であった。これらのデータは、生理的な温度勾配がヒトの胚の発生に影響を与えている可能性を示唆しています。

This work was designed to determine temperature conditions within the reproductive tract of the female pig and study their impact on assisted reproductive technologies. Temperatures were recorded using a laparo-endoscopic single-site surgery assisted approach and a miniaturised probe. Sows and gilts were used to address natural cycle and ovarian stimulation treatments, respectively. According to in-vivo values, invitro fertilisation was performed at three temperature conditions (37.0 °C, 38.5 °C and 39.5 °C) and presumptive zygotes were cultured in these conditions for 20 hours while further embryo culture (21-168 hours post-insemination) was maintained at 38.5 °C. After 20 hours, different fertility parameters were assessed. During embryo culture, cleavage and blastocyst stages were evaluated. Sperm membrane fluidity at the experimental temperatures was studied by using differential scanning calorimetry and fluorescence recovery after photobleaching techniques. An increasing temperature gradient of 1.5 °C was found between the oviduct and uterus of sows (p < 0.05) and when this gradient was transferred to pig in-vitro culture, the number of poly-nuclear zygotes after in-vitro fertilisation was reduced and the percentage of blastocysts was increased. Moreover, the temperature transition phase for the boar sperm membrane (37.0 °C) coincided with the temperature registered in the sow oviduct, and sperm membranes were more fluid at 37.0 °C compared with that of sperm incubated at higher temperatures (38.5 and 39.5 °C). These data suggest that there may be an impact of physiological temperature gradients on human embryo development.

© The Author(s) 2020. Published by Oxford University Press on behalf of European Society of Human Reproduction and Embryology. All rights reserved. For permissions, please email: journals.permissions@oup.com.