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ectoderm n.1.外胚層。2.外層。短語和例子-al, -ic a...

ectogenesis

Ranging from 100 to 200 microns across , the width of several human hairs , these microscopic fossils are surprisingly complex and constitute almost a textbook example of a bilaterian , including the three major tissue layers ( the endoderm , mesoderm and ectoderm familiar from high school biology texts ) , the presence of a gut with a mouth and anus , and paired coeloms ( body cavities ) surrounding the gut 這些微化石的大小為100 ~ 200微米,相當于幾根頭發的寬度, ?們看起來出奇復雜,而且簡直就像兩側對稱動物的教科書般,展示了各種特徵:包括三個主要的組織層(內胚層、中胚層及外胚層,都是中學生物課本中熟悉的名詞) ,前后連接口部與肛門的腸腔,腸腔外還圍繞著成對的體腔。