基本解释扁上皮细胞同根派生 英汉例句Morphology of a Simple Sponge. (a) In this example, pinacocytes form the outer body wall, and mesenchyme cells and spicules are in the mesohyl. 由于鞭毛摆动引起水流通过海绵体，获得食物颗粒和氧。