The diagram describes the six steps
of the test-tube baby protocol, more commonly referred to as in vitro fertilization,
IVF. Which number corresponds to the
steps of in vitro fertilization, external fertilization, of the eggs by sperm? (A) Six, (B) three, (C) four, (D)
In vitro fertilization is a
procedure where the egg and sperm are combined outside the body to create an
embryo. This embryo can then be transferred
to the uterus where it can implant and create a pregnancy. In the first step of IVF, the
biological female takes hormones to stimulate the ovaries to produce multiple
eggs. These eggs are then extracted from
the ovaries, along with sperm from the biological male.
The eggs and sperm are then
combined in the laboratory in a special dish called a Petri dish. Here, fertilization can occur in
the dish. The dish is incubated to maintain a
physiological temperature and pH to mimic the Fallopian tube where fertilization
normally occurs. Over the course of a few days, the
fertilized egg develops into an embryo. Finally, the embryo is transferred
to the uterus where it can implant and form a pregnancy.
The step that correctly identifies
fertilization during IVF is shown here and is given by answer choice (C), four.