① 胎盘实质呈双叶或多叶，以双叶胎盘（bilobed placenta）多见，发生率为2-8%。 ② 胎盘两叶完全分开，两叶间有胎膜及薄层蜕膜相连，称为双叶胎盘。 2、发生机制与病理生理 ① 受精卵着床后，底蜕膜血管分布不均，呈局灶状分布，部分供应不足，在血管丰富的 ...

SYDNEY, June 3 (Xinhua) -- About 3.64 percent of the population, or one in 28 Australians, may be affected by Fetal Alcohol Spectrum Disorder (FASD), a lifelong neurodevelopmental condition caused by ...