Why is it that only one sperm out of the hundreds (or thousands) available enters the oocyte?

The pre-embryo develops into a multicellular complex known as a 

(a) Blastocyst

(b) Trophoblast

(c) Lacuna

(d) Blastomere

List the factors involved in initiating labor contractions.

Which of the following changes occur in the baby’s cardiovascular system after birth?

(a) umbilical arteries and vein become fibrosed

(b) pulmonary circulation begins to function, and pressure in the left side of the heart increases

(c) the ductus venosus becomes obliterated, as does the ductus arteriosus

(d) all of these

The most important hormone in initiating and maintaining lactation after birth is

(a) estrogen

(b) FSH

(c) prolactin

(d) oxytocin

True or False (if false, choose the answer that would correct the statement): Conception is the moment an embryo begins to develop.