Klein S, Rokitta M, Baulain U, Thielebein J, Haase A, Ellendorff F
Institute for Animal Science and Animal Behaviour Mariensee, Federal Agricultural Research Center, Neustadt, Germany.
Poult Sci. 2002 Apr;81(4):529-36. doi: 10.1093/ps/81.4.529.
At the time of oviposition, the embryo in the fertilized chicken egg has developed the germinal disc on top of the yolk and contains thousands of blastodermal cells. The germinal disc escapes exact localization because it is surrounded by albumen and shell membranes under a calcified shell. This study investigated whether or not ultrasonography or nuclear magnetic resonance imaging (MRI) are suited to localize the germinal disc and, if so, to estimate the accuracy of localization. Hatchability of treated eggs was also recorded. The ultrasound waves were reflected by the shell. The germinal disc could be seen only after removal of the eggshell and the outer shell membrane. In all, 39 intact eggs, MRI localized the germinal disc within 2 mm thick image slices. The mean position of the germinal disc deviated 3.0+/-2.1 mm from the maximum vertical plane of the egg with a mean distance to the inner surface of the shell of 2.7+/-1.1 mm. Incubation resulted in 84.2 and 77.5% hatched chicks for imaged eggs and controls, respectively. The localization results of MRI were verified manually in 38 open shell cultures. Correlation coefficients for the position of the germinal disc were r = 0.86 to 0.99 for the x-axis, r = 0.75 to 0.89 for the y-axis, and r = 0.63 to 0.76 for the z-axis. The study thus shows that MRI is a reliable tool to localize the germinal disc within the intact freshly laid egg.
在产卵时，受精鸡蛋中的胚胎已在蛋黄顶部发育出胚盘，其中包含数千个胚盘细胞。胚盘难以精确定位，因为它被蛋白和钙化蛋壳下的壳膜所包围。本研究调查了超声检查或核磁共振成像（MRI）是否适合定位胚盘，如果适合，评估定位的准确性。还记录了处理过的鸡蛋的孵化率。超声波被蛋壳反射。只有去除蛋壳和外壳膜后才能看到胚盘。总共39个完整鸡蛋，MRI在2毫米厚的图像切片中定位了胚盘。胚盘的平均位置与鸡蛋最大垂直平面的偏差为3.0±2.1毫米，到蛋壳内表面的平均距离为2.7±1.1毫米。成像鸡蛋和对照的孵化率分别为84.2%和77.5%。在38个开壳培养物中手动验证了MRI的定位结果。胚盘位置的相关系数在x轴上为r = 0.86至0.99，在y轴上为r = 0.75至0.89，在z轴上为r = 0.63至0.76。因此，该研究表明MRI是在刚产下的完整鸡蛋中定位胚盘的可靠工具。
