gastrula stage meaning in English

原肠胚期4
原肠胚期４

The embryonic shield appeared in 15h , and the fertilized egg entered the middle gastrula stage
15小时出现胚盾， 15小时55分，胚体下包一半。
The fertil ized egg entered the early gastrula stage in 11h45min , the germ ring appeared , and the oil globules diffused in the plant hemisphere in this stage
11小时45分囊胚开始下包，胚环出现，油球出现重新扩散的现象。