I think the correct answer would be A. The yolk sac becomes the placenta. It is membranous sac that is attached to the embryo. It provides all the nutrition and the blood cells needed by the embryo. It is also called the umbilical vesicle.
They were completely heterophic in nature because it allowed them to absorb different material from the environment as an energy source
Answer:
Neural stem cells are normally found within the brain and spinal cord. NSCs are specialized stem cells that can differentiate into the cell types of the central nervous system, including neurons and glial cells
Explanation:
Cytosine, thiamine, uracil are prima de bases. ade dune and guanche are purine bases.
