Explanation

During gastrulation, the upper layer formed is called the epiblast. 

During the early stages of embryonic development, a process called gastrulation transforms a bilaminar disk (consisting of the epiblast and hypoblast) into a trilaminar disk.

The epiblast is the upper layer, while the hypoblast is the lower layer.

The epiblast eventually develops into the ectoderm.