基本解释n.脊索同根派生 英汉例句That is, the growth cones collapsed. 2. In the 4th embryonicday (E4), sema 3A mRNA was expressed around the neural tube and atthe notocord. 在鸡胚发育的第 4天（E4），Sema 3A InRN表阴神经管周围和脊索。