Branum Sylvia, Tazawa Hiroshi, Burggren Warren
Developmental Integrative Biology, Department of Biological Sciences, University of North Texas, Denton, TX, United States.
Front Physiol. 2022 May 24;13:880737. doi: 10.3389/fphys.2022.880737. eCollection 2022.
Variations from a relative humidity (RH) of ∼50-60% can unfavorably alter chicken embryo development, but little is known of whether the embryo can mitigate these effects through physiological regulation. We examined effects of Low RH (25-35%), and High RH (85-93%) compared to Control RH (50-60%) on hatchability, embryonic growth, hematology and blood gases and pH. Mean hatchability was not affected by RH. Yet, Low RH decreased wet body mass of advanced embryos (days 17-19; d17-19), with lowered body water content compared with embryos of Control and High RH. However, dry body mass of developing (d11-19) embryos was not different between the three RH groups. Mean blood osmolality across development was higher in Low RH embryos and lower in High RH embryos compared with Control embryos. Mean blood lactate was higher in both Low and High RH embryos compared to Control embryos. Unexpectedly, hematological respiratory variables (Hct, [RBC], MCV, [Hb]) and blood gas variables (Po, Pco, pH, [HCO ]) across development were not affected by RH. Mean wet body mass at hatch (d20-22) was larger in High RH embryos compared with Low RH embryos, but mean wet and dry body mass upon euthanasia on d22 was unaffected. The ability of the three populations to physiologically regulate blood respiratory variables and blood acid-base balance was then examined by observing their responses to intrinsic hypoxemia and hypercapnia created by controlled partial egg submersion in water. Hct and [RBC] responses were less disturbed by submersion in High RH embryos compared with both Control and Low RH embryos, which showed major disturbance. Acid-base regulatory responses did not differ between RH groups. We conclude that, while different incubation RHs cause large differences in tissue water content and body mass, most hematological and acid-base regulatory capabilities are regulated near Control values.
相对湿度（RH）偏离约50 - 60%会对鸡胚发育产生不利影响，但关于胚胎是否能通过生理调节减轻这些影响却知之甚少。我们研究了与对照相对湿度（50 - 60%）相比，低相对湿度（25 - 35%）和高相对湿度（85 - 93%）对孵化率、胚胎生长、血液学、血气和pH值的影响。平均孵化率不受相对湿度影响。然而，低相对湿度降低了晚期胚胎（第17 - 19天；d17 - 19）的湿体重，与对照和高相对湿度的胚胎相比，其体内水分含量降低。然而，在三个相对湿度组中，发育中（d11 - 19）胚胎的干体重没有差异。与对照胚胎相比，低相对湿度胚胎发育过程中的平均血液渗透压较高，高相对湿度胚胎的平均血液渗透压较低。与对照胚胎相比，低相对湿度和高相对湿度胚胎的平均血液乳酸含量均较高。出乎意料的是，发育过程中的血液学呼吸变量（红细胞压积、[红细胞]、平均红细胞体积、[血红蛋白]）和血气变量（氧分压、二氧化碳分压、pH值、[碳酸氢根]）不受相对湿度影响。与低相对湿度胚胎相比，高相对湿度胚胎出雏时（d20 - 22）的平均湿体重更大，但在d22处安乐死时的平均湿体重和干体重不受影响。然后通过观察三组对控制部分卵浸入水中所产生的内源性低氧血症和高碳酸血症的反应，研究了它们生理调节血液呼吸变量和血液酸碱平衡的能力。与对照和低相对湿度胚胎相比，高相对湿度胚胎浸入水中时红细胞压积和[红细胞]的反应受干扰较小，对照和低相对湿度胚胎表现出较大干扰。相对湿度组之间的酸碱调节反应没有差异。我们得出结论，虽然不同的孵化相对湿度会导致组织含水量和体重存在很大差异，但大多数血液学和酸碱调节能力在接近对照值的水平上受到调节。
