Final answer:
The placenta, developed from the mother's endometrium and the embryo's chorionic membrane, is the structure that facilitates material exchange between the mother and fetus.
Step-by-step explanation:
The Placenta and Fetal Development
The structure that allows exchange of materials in both directions between the mother and the embryo is the placenta. This vital organ is developed jointly from the mother's endometrium and the embryo's chorionic membrane. It serves as a lifeline between the mother and the fetus, facilitating the transfer of oxygen, nutrients, and waste. The umbilical cord, which contains two arteries and a vein, connects the fetus to the placenta. It allows blood from the fetus to enter the placenta through the umbilical arteries where it exchanges gases and other substances with the mother's blood before returning to the fetus through the umbilical vein. The placenta is designed to enable this exchange while preventing the mother's and fetus's blood from mixing, which is crucial for protecting the fetus from potential immune reactions.
Substances such as alcohol, nicotine, and certain pathogens can pass through the placenta and may be harmful to fetal development, leading to potential conditions like fetal alcohol spectrum disorders (FASD). Therefore, pregnant individuals are advised to avoid fetotoxic substances. The placenta's functions are essential for the growing embryo and continue to play an important role throughout gestation as the demands for nutrient and gas exchange increase.
Correct answer choice to the question is option c. the mother's endometrium and the embryo's chorionic membrane.