The asymmetry of avian egg-shape: an adaptation for reproduction on dry land
The asymmetry of avian egg-shape: an adaptation for reproduction on dry land
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DOI：
10.1111/j.1469-7580.2007.00737.x
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发表时间：
2007-06-01
影响因子：
2.4
通讯作者：
Yoshizaki, Norio
中科院分区：
文献类型：
--
作者：
Mao, Kun-Ming;Murakami, Ayako;Yoshizaki, Norio
本文以鹌鹑为研究对象，阐述了鸟类繁殖中不对称形状的生物学意义。在卵的孵化过程中，水分逐渐流失，钝端内外壳膜之间的气室膨胀，因此卵长轴与水平线的夹角增大，可能是因为卵内物的重心向尖端移动。角度增加发生在可育卵和不育卵中，这表明这种现象与生育能力无关，是由于形状不对称。气室体积的增加导致气室内壳膜面积的增加，以满足发育中的胚胎为更好地孵化所需的气体交换量。我们从内壳膜中分离出一个300 kda的蛋白。它是由输卵管峡管腔上皮细胞产生的，在壳膜纤维的皮层和气室周围的衬里中发现。子宫内膜包括子宫卵内、外壳膜之间的内层。不对称的椭球体在鸟蛋停留于输卵管峡部时，在其钝端产生气室，以便在产卵后保持钝端，在干燥环境下孵化时使钝端升高，从而提高了孵化率。
The present study describes the biological meaning of the asymmetrical shape in avian reproduction using quail. During the incubation of eggs, water was gradually lost and the air chamber which appeared in between the inner and outer shell membranes at the blunt end expanded, so that the angle made by the long egg-axis and the horizontal line increased, presumably because the centre of gravity of the egg contents moved toward the sharp end. The increase in angle occurred in both fertile and infertile eggs, suggesting that this phenomenon occurs irrespective of fertility and is due to the asymmetrical shape. The increase in the volume of the air chamber resulted in an increase in the area of the inner shell membrane at the chamber to satisfy the amount of gas exchange needed by the developing embryo for better hatching. We isolated a 300-kDa protein from the inner shell membrane. It was produced by cells in the luminal epithelium of the oviductal isthmus and was found in the cortex of the fibres of shell membranes and a lining surrounding the air chamber. The lining comprised a medial layer between the inner and outer shell membranes in uterine eggs. The asymmetrical ellipsoid produces the air chamber at the blunt end of the avian egg during its sojourn in the oviductal isthmus, to maintain the blunt end up after oviposition and to raise that end during incubation in a dry environment, leading to high hatchability.