Final answer:
The intestine's temporary location in the umbilical cord during the embryonic period is due to the embryonic abdomen's insufficiency in size to hold the rapidly developing intestines.
Step-by-step explanation:
The development of the gastrointestinal system during the embryonic period involves the intestines temporarily remaining within the umbilical cord. This occurs because the embryonic abdomen is too small to accommodate the rapidly developing intestines. Thus, during the sixth week of development, the intestines loop into the umbilical cord as a temporary adaptation. This process is part of the overall mechanism wherein the embryo, starting as a flat sheet of cells, begins to fold and create a more complex structure including the primitive gut lined by the endoderm. The placenta and umbilical cord facilitate vital functions, providing oxygen and nutrients from the mother to the developing embryo and, later, the fetus, via the umbilical vein and arteries.