Could you tell me what the yellow mass within the blastocoel is called ? I know that blastocoel is a fluid filled cavity, so are the yellow coloured cells the inner part of blastoderm or are they some other cells ?
If they are the part of blastoderm itself, why is it not in the same colour of light-orange as the blastoderm, or is it the mesoderm, or the inner cell mass ?
And is it the blastoderm that forms ectoderm , and endoderm pinches off the ectoderm during gastrula phase? And could you also explain how the orange mesoderm formed ?