Embryonic development is divided into trimesters. Each list below shows the development that normally occurs during one trimester, though the lists are not in chronological order. Hair on skin, organs functioning, sleep cycle eyelids, major organs, fingernails eyes open and close, fastest weight gain

Once an egg cell is fertilized by sperm, the cell then, as the embryo develops, it receives nourishment and eliminates wastes by transferring substances from its blood to its mother's blood. a. becomes a fetus immediately and exits the womb b. begins to divide and implants itself in the wall of the uterus c. remains in the uterus without dividing for several months d. travels back to the ovaries until the fetus is developed