The structure that connects the placenta and the fetus is the __________________ __________________, which has __________________ artery(ies) and __________________ vein(s).
Fill in the blank(s) with correct word
Question 2
Which of the following structures closes over the trachea to protect it during swallowing?
A) Epiglottis B) Diaphragm C) Pharynx D) Cricoid cartilage