The outermost layer of cells or tissue of an embryo in early development

The middle layer of an embryo in early development, situated between the [[外胚层|外胚層|wai4 pei1 ceng2]] and [[内胚层|內胚層|nei4 pei1 ceng2]].

the innermost layer of cells or tissue of an embryo in early development; endoblast; entoderm

triploblastic animal; any animal having three primary germ layers