Ealy A D, Hansen P J
Department of Dairy and Poultry Sciences, University of Florida, Gainesville 32611.
J Cell Physiol. 1994 Sep;160(3):463-8. doi: 10.1002/jcp.1041600309.
During early development, elevated temperatures have deleterious effects on embryonic viability and development. The primary objective of the current study was to determine the ontogeny of induced thermotolerance during early murine embryonic development. Embryos were either retrieved from superovulated ICR female mice at the 2 cell and 4 cell stages and cultured thereafter or were retrieved from oviducts or uterine horns at the desired stage of development. Induction of thermotolerance was detected by evaluating viability and further development after embryos were exposed to homeothermic temperature (37 degrees C), mild heat shock (40 degrees C for 1 h), severe heat shock (42 degrees C for 1 h or 43 degrees C for 2 h), or mild heat shock followed by severe heat shock (to induce thermotolerance). Induction of thermotolerance was observed beginning at the 8 cell stage when embryos were developed in culture from the 2 cell to 4 cell stage. When embryos were developed in vivo (i.e., were retrieved from the reproductive tract at the desired stage of development), thermotolerance was not induced until the blastocyst stage of development. The induction of thermotolerance was dependent on serum supplementation since induction of thermotolerance was not observed when embryos were placed in medium without serum. Induced thermotolerance could also be demonstrated in bovine blastocysts. In conclusion, embryos acquire the ability to undergo thermotolerance as they progress through development. The timing of processes leading to acquisition of thermotolerance can, however, be hastened by exposure of embryos to in vitro conditions.
在早期发育过程中，体温升高对胚胎的生存能力和发育具有有害影响。本研究的主要目的是确定小鼠早期胚胎发育过程中诱导耐热性的个体发生情况。胚胎要么在2细胞和4细胞阶段从超排卵的ICR雌性小鼠中获取，然后进行培养，要么在发育的特定阶段从输卵管或子宫角中获取。通过评估胚胎在暴露于体温（37℃）、轻度热休克（40℃ 1小时）、重度热休克（42℃ 1小时或43℃ 2小时）或轻度热休克后再进行重度热休克（以诱导耐热性）后的生存能力和进一步发育情况，来检测耐热性的诱导。当胚胎从2细胞阶段培养到4细胞阶段并发育到8细胞阶段时，观察到耐热性的诱导。当胚胎在体内发育（即，在发育的特定阶段从生殖道中获取）时，直到发育到囊胚阶段才诱导出耐热性。耐热性的诱导依赖于血清补充，因为当胚胎置于无血清培养基中时未观察到耐热性的诱导。诱导的耐热性在牛囊胚中也得到了证实。总之，胚胎在发育过程中获得了耐热的能力。然而，通过使胚胎暴露于体外条件下，可以加速导致获得耐热性的过程的时间。
