mesoderm
The mesoderm forms: skeletal muscle, the skeleton, the dermis of skin, connective tissue, the urogenital system, the heart, blood (lymph cells), the kidney, and the spleen.
Mesoderm
It develops from the endoderm germ layer
Gastrulation is first step towards germ layer development .
Porifera, which includes sponges, do not have true germ layers like other animals. They lack specialized tissues and organs, making them the simplest multicellular organisms.
ectoderm.
endoderm
endoderm
Ectoderm
If your question is 'Is the trophoblast present during germ layer formation (i.e. gastrulation) ?' then the answer is YES
Mesoderm forms muscles .
The mesoderm
Skin develops from ectoderm.
The endoderm is the germ layer that will become the inner lying of the body cavity as well as on the surface of the organs. Meaning of endoderm is: Endo- = within, plus derm = germ or from.