HUMAN BIOLOGY

reprodUCtIVe systeMs 319

hoW may assisted reproductive technologies

help overcome infertility?

• Fertility drugs include hormones that stimulate ovulation.


• In vitro fertilization, artificial insemination, and intrafallopian
  transfers are techniques for producing an embryo that may be
  transferred to a prospective mother’s body.

taKe-hoMe Message

20 percent of the time, a normal pregnancy follows. An

alternative is ZIFT (zygote intrafallopian transfer). First,

oocytes and sperm are placed in a laboratory dish. If fertil-

ization occurs, the zygote is placed in a woman’s oviducts.

GIFT and ZIFT have about the same success rate as in

vitro fertilization.

Intracytoplasmic sperm injection, or ICSI, is a variation
on IVF. A single sperm is injected into an egg with a tiny
glass needle. Although IVF and ICSI are both in common
use, evidence is mounting that babies conceived through any
form of in vitro fertilization have a much higher risk of low
birth weight and related developmental problems later on.
In artificial insemination with embryo transfer (Figure 16.15),
a fertile female volunteer is inseminated with sperm from
a man whose female partner is infertile. If a pregnancy
results, the developing embryo is transferred to the infertile
woman’s uterus or to a “surrogate mother.” This approach
is technically difficult and has major legal complications. It
isn’t a common solution to infertility.
In GIFT (gamete intrafallopian transfer), sperm and
oocytes are collected and placed into an oviduct. About

F i g u r e 16.15 Various options exist for assisted reproductive technologies.

(© Cengage Learning)

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+=

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1. Father is infertile. Mother is
   inseminated by donor and carries child.


2. 
   
   
   
   2. 
      
   
   
   
   

3.

4.

5.

6.

7.

3.

4.

1. Mother is fertile but unable to conceive.
   Egg from mother and sperm from father
   are combined in laboratory. Embryo is
   placed in mother’s uterus.

Father is infertile and mother is fertile but

unable to conceive. Egg from mother is

combined with sperm from donor.

+=

+=

Mother is infertile and unable to carry

child. Egg of donor is combined with sperm

from father. Embryo is transferred to donor

(also see number 3, column at left).

+=

Both parents are fertile, but mother is

unable to carry child. Egg from mother

and sperm from father are combined.

Embryo is transferred to donor.

+=

Father is infertile. Mother is fertile but

unable to carry child. Egg from mother

is combined with sperm from donor.

Embryo is transferred to surrogate

mother.

+=

+=

+=

+=

Sperm from father

Egg from mother

Baby born of mother

Sperm from donor

Egg from donor

Baby born of donor

(surrogate)

KEY

Artificial Insemination

and Embryo Transfer In Vitro^ Fertilization (IVF)

Mother is infertile but able to carry child.

Egg from donor is combined with sperm

from father and implanted in mother.

Mother is infertile but able to carry

child. Donor egg is inseminated by

father via IVF. Embryo is transferred

and mother carries child.

Mother is infertile and unable to carry

child. Donor of egg is inseminated by

father and carries child.

Both parents are infertile, but

mother is able to carry child. Donor

egg is inseminated by sperm donor

via IVF. Embryo is transferred and

mother carries child.

Both parents are infertile, but mother is

able to carry child. Egg and sperm

from donors are combined in laboratory

(also see number 4, column at left).

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