Mieusset R, Quintana Casares P, Sanchez Partida L G, Sowerbutts S F, Zupp J L, Setchell B P
Department of Animal Sciences, Waite Agricultural Research Institute, University of Adelaide, Glen Osmond, Australia.
J Reprod Fertil. 1992 Mar;94(2):337-43. doi: 10.1530/jrf.0.0940337.
Fertilization rate and embryonic mortality were assessed in 636 ewes inseminated in each uterine horn with 50 x 10(6) frozen spermatozoa from four control rams and from four rams submitted to a moderate (1.4-2.2 degrees C), but repeated, intermittent (16 h/day for 21 consecutive days) increase in their subcutaneous scrotal temperature by means of scrotal insulation. Pregnancy was assessed twice in each ewe from concentration of progesterone in blood plasma at 17 days and by ultrasound at 65 days after insemination. No differences were observed in the pregnancy rate at 17 days between ewes inseminated with semen collected from control rams (56.0, 65.2, 66.7 and 60.3%) and from heated rams (60.6, 71.8, 63.6 and 48.2%) before or after 4, 15 and 21 days of heating, respectively. In contrast, the rate of embryonic mortality between 17 and 65 days after insemination was significantly higher at days 4, 15 and 21 in the heated rams (78.7, 78.6 and 93%) than in the control rams (55, 59 and 65.7%). These results indicate that an intermittent slight, but repeated, increase in the subcutaneous scrotal temperature could induce a significant increase in the embryonic mortality rate. As these changes were apparent on day 4 of heating, an effect must have occurred on sperm stored in the epididymis.
对636只母羊进行研究，分别向其每个子宫角内输精50×10⁶个来自4只对照公羊以及4只通过阴囊保温使其阴囊皮下温度适度（1.4 - 2.2摄氏度）但反复间歇性（连续21天每天16小时）升高的公羊的冷冻精子，评估受精率和胚胎死亡率。在授精后17天通过检测血浆孕酮浓度以及65天通过超声对每只母羊进行两次妊娠评估。在加热前、加热4天、15天和21天后，用从对照公羊采集的精液（受精率分别为56.0%、65.2%、66.7%和60.3%）和加热公羊采集的精液（受精率分别为60.6%、71.8%、63.6%和48.2%）输精的母羊，在17天时的妊娠率未观察到差异。相比之下，授精后17至65天期间，加热公羊在加热4天、15天和21天时的胚胎死亡率（分别为78.7%、78.6%和93%）显著高于对照公羊（分别为55%、59%和65.7%）。这些结果表明，阴囊皮下温度间歇性轻微但反复升高会导致胚胎死亡率显著增加。由于这些变化在加热第4天就很明显，所以必定对附睾中储存的精子产生了影响。
