Download Chapter 46

Chapter 46
Animal Reproduction
PowerPoint Lectures for
Biology, Seventh Edition
Neil Campbell and Jane Reece
Lectures by Chris Romero
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Overview: Doubling Up for Sexual
Reproduction
• The two earthworms in this picture are mating
• Each worm produces both sperm and eggs,
which will fertilize
– And in a few weeks, new worms will hatch
Figure 46.1
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Concept 46.1: Both asexual and sexual
reproduction occur in the animal kingdom
• Asexual reproduction is the creation of new
individuals
– Whose genes all come from one parent
• Sexual reproduction is the creation of offspring
– By the fusion of male and female gametes to
form a zygote
• The female gamete is the egg
• The male gamete is the sperm
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Mechanisms of Asexual Reproduction
• Many invertebrates reproduce asexually by
fission
– The separation of a parent into two or more
individuals of approximately the same size
Figure 46.2
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Also common in invertebrates is
budding
– In which two new individuals arise
from outgrowths of existing ones
• Another type of asexual reproduction
is fragmentation, which
– Is the breaking of the body into
several pieces, some or all of which
develop into complete adults
– Must be accompanied by
regeneration, the regrowth of lost
body parts
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Reproductive Cycles and Patterns
• Most animals exhibit cycles in reproductive
activity
– Often related to changing seasons
• Reproductive cycles
– Are controlled by hormones and environmental
cues
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Animals may reproduce exclusively asexually or sexually or they
may alternate between the two
• Some animals reproduce by parthenogenesis
–
A process in which an egg develops without being fertilized
–
Among vertebrates, several genera of fishes, amphibians, and
lizards, including whiptail lizards
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Sexual reproduction presents a special
problem for certain organisms
– That seldom encounter a mate
• One solution to this problem is
hermaphroditism
– In which each individual has both male and
female reproductive systems
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Another remarkable reproductive pattern is
sequential hermaphroditism
– In which an individual reverses its sex during
its lifetime
Figure 46.4
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Concept 46.2: Fertilization depends on
mechanisms that help sperm meet eggs of the
same species
• The mechanisms of fertilization, the union of
egg and sperm
– Play an important part in sexual reproduction
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Some species have external fertilization, in
which
– Eggs shed by the female are fertilized by
sperm in the external environment
Eggs
Figure 46.5
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Other species have internal fertilization, in
which
– Sperm are deposited in or near the female
reproductive tract, and fertilization occurs
within the tract
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• In either situation, fertilization requires critical
timing
– Often mediated by environmental cues,
pheromones, and/or courtship behavior
• Internal fertilization
– Requires important behavioral interactions
between male and female animals
– Requires compatible copulatory organs
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Ensuring the Survival of Offspring
• All species produce more offspring than the
environment can handle
– But the proportion that survives is quite small
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• The embryos of many terrestrial animals
– Develop in eggs that can withstand harsh
environments
• Instead of secreting a shell around the embryo
– Many animals retain the embryo, which
develops inside the female
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Many different types of animals
– Exhibit parental care to ensure survival of
offspring
Figure 46.6
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Gamete Production and Delivery
• To reproduce sexually
– Animals must have systems that produce
gametes
• The least complex systems
– Do not even contain distinct gonads, the
organs that produce gametes in most animals
• The most complex reproductive systems
– Contain many sets of accessory tubes and
glands that carry, nourish, and protect the
gametes and the developing embryos
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Many animals with relatively simple body plans
– Possess highly complex reproductive systems
Genital
pore
(Digestive tract)
Female organs:
Male organs:
3 Uterus
4 Seminal
vesicle
Yolk gland
Yolk duct
3 Sperm duct
(vas deferens)
2 Oviduct
1 Ovary
2
Vas efferens
1 Testis
Seminal
receptacle
Figure 46.7
(Excretory pore)
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Most insects
– Have separate sexes with complex
reproductive systems
1 Ovary
Accessory
gland
1 Testis
4 Ejaculatory
duct
2 Vas deferens
5 Penis
3 Seminal
vesicle
(a) Male honeybee. Sperm form in the testes,
pass through the sperm duct (vas deferens),
and are stored in the seminal vesicle.
The male ejaculates sperm along with fluid
from the accessory glands. (Males of some
species of insects and other arthropods have
appendages called claspers that grasp the
Figure 46.8a, b female during copulation.)
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Oviduct
Spermatheca
3 Vagina
Accessory
gland
(b) Female honeybee. Eggs develop in
the ovaries and then pass through the
oviducts and into the vagina. A pair of
accessory glands (only one is shown)
add protective secretions to the eggs
in the vagina. After mating, sperm are
stored in the spermatheca, a sac
connected to the vagina by a short duct.
Female Reproductive Anatomy
• The female external reproductive structures
include
– The clitoris
– Two sets of labia
• The internal organs are a pair of gonads
– And a system of ducts and chambers that
carry gametes and house the embryo and
fetus
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Reproductive anatomy of the human female
Uterus
Oviduct
(Urinary bladder)
(Pubic bone)
Ovary
(Rectum)
Cervix
Vagina
Urethra
Shaft
Glans
Bartholin’s gland
Prepuce
Vaginal opening
Figure 46.9
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Labia minora
Labia majora
Clitoris
Ovaries
Oviduct
Follicles
Uterus
Uterine wall
Endometrium
Corpus luteum
Cervix
Vagina
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Ovaries
• The female gonads, the ovaries
– Lie in the abdominal cavity
• Each ovary
– Is enclosed in a tough protective capsule and
contains many follicles
• A follicle
– Consists of one egg cell surrounded by one or
more layers of follicle cells
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• The process of ovulation
– Expels an egg cell from the follicle
• The remaining follicular tissue then grows within the
ovary
– To form a solid mass called the corpus luteum, which
secretes hormones, depending on whether or not
pregnancy occurs
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Oviducts and Uterus
• The egg cell is released into the abdominal
cavity
– Near the opening of the oviduct, or fallopian
tube
• Cilia in the tube
– Convey the egg to the uterus
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Vagina and Vulva
• The vagina is a thin-walled chamber
– That is the repository for sperm during
copulation
– That serves as the birth canal through which a
baby is born
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• The vagina opens to the outside at the vulva
– Which includes the hymen, vestibule, labia
minora, labia majora, and clitoris
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Mammary Glands
• The mammary glands are not part of the
reproductive system
– But are important to mammalian reproduction
• Within the glands
– Small sacs of epithelial tissue secrete milk
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Male Reproductive Anatomy
• In most mammalian species
– The male’s external reproductive organs are
the scrotum and penis
• The internal organs
– Consist of the gonads, which produce sperm
and hormones, and accessory glands
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Reproductive anatomy of the human male
Seminal
vesicle
(behind
bladder)
(Urinary
bladder)
Prostate gland
Urethra
Scrotum
Glans penis
Figure 46.10
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Bulbourethral
gland
Erectile tissue
of penis
Vas deferens
Epididymis
Testis
(Urinary
bladder)
Seminal vesicle
(Rectum)
(Pubic bone)
Erectile
tissue of
penis
Vas deferens
Ejaculatory duct
Prostate gland
Bulbourethral gland
Urethra
Vas deferens Epididymis
Glans penis
Testis
Scrotum
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Prepuce
Testes
• The male gonads, or testes
– Consist of many highly coiled tubes
surrounded by several layers of connective
tissue
• The tubes are seminiferous tubules
– Where sperm form
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Production of normal sperm
– Cannot occur at the body temperatures of
most mammals
• The testes of humans and many mammals
– Are held outside the abdominal cavity in the
scrotum, where the temperature is lower than
in the abdominal cavity
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Ducts
• From the seminiferous tubules of a testis
– The sperm pass into the coiled tubules of the
epididymis
• During ejaculation
– Sperm are propelled through the muscular vas
deferens, the ejaculatory duct, and exit the
penis through the urethra
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Glands
• Three sets of accessory glands
–
Add secretions to the semen, the fluid that is ejaculated
• A pair of seminal vesicles
–
Contributes about 60% of the total volume of semen
• The prostate gland
–
Secretes its products directly into the urethra through several
small ducts
• The bulbourethral gland
–
Secretes a clear mucus before ejaculation that neutralizes acidic
urine remaining in the urethra
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Semen in the Female Reproductive Tract
• Once in the female reproductive tract
– A number of processes, including contractions
of the uterus, help move the sperm up the
uterus
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Penis
• The human penis
– Is composed of three cylinders of spongy
erectile tissue
• During sexual arousal
– The erectile tissue fills with blood from the
arteries, causing an erection
–
How does nitric oxide work again?
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Human Sexual Response
• Two types of physiological reactions
predominate in both sexes
– Vasocongestion, the filling of tissue with blood
– Myotonia, increased muscle tension
• The sexual response cycle can be divided into
four phases
– Excitement, plateau, orgasm, and resolution
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Concept 46.4: In humans and other mammals,
a complex interplay of hormones regulates
gametogenesis
• The process of gametogenesis
– Is based on meiosis, but differs in females and
males
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Oogenesis is the development of mature ova
Ovary
Primary germ cell in embryo
Differentiation
Oogonium
in ovary
Oogonium
2n
Mitotic
division
Primary
oocyte
within
follicle
Primary oocyte,
arrested in prophase
of meiosis I
(present at birth)
2n
Growing
follicle
Completion of meiosis I
and onset of meiosis II
n
First
polar
body
n
Secondary oocyte,
arrested at metaphase of meiosis II
Ovulation
n
n
Entry of
sperm triggers
completion of
meiosis II
Mature follicle
Ruptured
follicle
Ovum
Ovulated
secondary oocyte
Corpus luteum
Figure 46.11
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Degenerating
corpus luteum
• Spermatogenesis is the production of mature
sperm
Epididymis
Seminiferous tubule
Testis
Cross section
of seminiferous
tubule
Spermatogonium
2n
Mitotic division,
producing large numbers
of spermatogonia
Sertoli cell
nucleus
Differentiation and
onset of meiosis I
Primary spermatocyte
(in prophase of meiosis I)
2n
Meiosis I completed
n
n
Secondary spermatocyte
Meiosis II
n
n
n
n
Early
spermatids
Lumen of
Seminiferous tubule
Spermatids
(at two stages of
differentiation)
Differentiation
(Sertoli cells provide
nutrients)
n
n
n
Sperm cells
n
Neck
Head
Midpiece
Tail
Plasma membrane
Mitochondria
Nucleus
Figure 46.12
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Acrosome
Oogenesis differs from spermatogenesis in three major ways
• First, during the meiotic divisions of oogenesis
– Cytokinesis is unequal, with almost all the
cytoplasm monopolized by a single daughter
cell, the secondary oocyte
• Second, sperm are produced continuously
throughout a male’s life
– Which is not the case in oogenesis
• Third, oogenesis has long “resting” periods
– While spermatogenesis produces sperm in
uninterrupted sequence
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
The Reproductive Cycles of Females
• In females
– The secretion of hormones and the
reproductive events they regulate are cyclic
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Menstrual Versus Estrous Cycles
• Two different types of cycles occur in females
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Humans and other primates have menstrual
cycles
– While other mammals have estrous cycles
• In both cases ovulation occurs at a time in the
cycle
– After the endometrium has started to thicken in
preparation for implantation
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• In menstrual cycles
– The endometrium is shed from the uterus in a
bleeding called menstruation
– Sexual receptivity is not limited to a specific
timeframe
• In estrous cycles
– The endometrium is reabsorbed by the uterus
– Sexual receptivity is limited to a “heat” period
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• The female reproductive cycle
– Is one integrated cycle involving two organs,
the uterus and ovaries
• Cyclic secretion of GnRH from the
hypothalamus
– And of FSH and LH from the anterior pituitary
orchestrates the female reproductive cycle
• Five kinds of hormones
– Participate in an elaborate scheme involving
both positive and negative feedback
–
Know these 5 hormones and their roles!
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• The reproductive cycle of the human female
(a)
Control by hypothalamus
Inhibited by combination of
estrogen and progesterone
Hypothalamus
1
Stimulated by high levels
of estrogen
GnRH
Anterior pituitary
LH
FSH
2
(b)
Inhibited by low levels of
estrogen
Pituitary gonadotropins
in blood
6
LH
3
(c)
FSH
FSH and LH stimulate
follicle to grow
Ovarian cycle
7
Growing follicle
Mature
follicle
8
Corpus
luteum
Ovulation
Follicular phase
4
(d)
LH surge triggers
ovulation
5
Estrogen
Peak causes
LH surge
10
Progesterone
Estrogen level
very low
(e)
Luteal phase
Progesterone and
estrogen secreted
by corpus luteum
Estrogen secreted
by growing follicle in
increasing amounts
Ovarian hormones
in blood
Degenerating
corpus luteum
9
Progesterone and estrogen promote thickening
of endometrium
Uterine (menstrual) cycle
Endometrium
Days
Menstrual flow phase
Figure 46.13a–e
0
5
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Proliferative phase
14 15
10
Secretory phase
20
25
28
The Ovarian Cycle
• In the ovarian cycle
– Hormones stimulate follicle growth, which
results in ovulation
• Following ovulation
– The follicular tissue left behind transforms into
the corpus luteum
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
The Uterine (Menstrual) Cycle
• Cycle after cycle
– The maturation and release of egg cells from
the ovary are integrated with changes in the
uterus
• If an embryo has not implanted in the
endometrium by the end of the secretory phase
– A new menstrual flow commences
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Menopause
• After about 450 cycles, human females
undergo menopause
– The cessation of ovulation and menstruation
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Hormonal Control of the Male Reproductive System
• Testosterone and other androgens
– Are directly responsible for the primary and
secondary sex characteristics of the male
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Androgen secretion and sperm production
– Are both controlled by hypothalamic and
pituitary hormones
Stimuli from other
areas in the brain
Hypothalamus
GnRH from the
hypothalamus regulates FSH and LH
release from the
anterior pituitary.
FSH acts on the
Sertoli cells of the
seminiferous
tubules, promoting
spermatogenesis.
Figure 46.14
Anterior
pituitary
Negative
feedback
LH stimulates the
Leydig cells to make
testosterone, which
in turn stimulates
sperm production.
Leydig cells
make
testosterone
Sertoli cells
Spermatogenesis
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Primary and
secondary sex
characteristics
Testis
Conception, Embryonic Development, and Birth
• Concept 46.5: In humans and other placental
mammals, an embryo grows into a newborn in
the mother’s uterus
• In humans and most other placental mammals
– Pregnancy, or gestation, is the condition of
carrying one or more embryos in the uterus
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Fertilization of an egg by a sperm, conception
– Occurs in the oviduct
3 Cleavage (cell division)
begins in the oviduct
as the embryo is moved
toward the uterus
by peristalsis and the
movements of cilia.
4 Cleavage continues.
By the time the embryo
reaches the uterus,
it is a ball of cells.
It floats in the uterus for
several days, nourished by
endometrial secretions. It
becomes a blastocyst.
Ovary
2 Fertilization occurs. A sperm
enters the oocyte; meiosis of
the oocyte finishes; and the
nuclei of the ovum and sperm
fuse, producing a zygote.
5 The blastocyst implants
in the endometrium
about 7 days after conception.
Uterus
1 Ovulation releases a
secondary oocyte, which
enters the oviduct.
(a) From ovulation to implantation
Endometrium
Endometrium
Inner cell mass
Cavity
Blastocyst
Figure 46.15a, b (b) Implantation of blastocyst
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Trophoblast
• After fertilization
– The zygote undergoes cleavage and develops
into a blastocyst before implantation in the
endometrium
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
First Trimester
• Human gestation
– Can be divided into three trimesters of about
three months each
• The first trimester
– Is the time of most radical change for both the
mother and the embryo
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• During its first 2 to 4 weeks of development
– The embryo obtains nutrients directly from the
endometrium
• Meanwhile, the outer layer of the blastocyst
– Mingles with the endometrium and eventually
forms the placenta
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Blood from the embryo
– Travels to the placenta through arteries of the
umbilical cord and returns via the umbilical vein
Maternal
arteries
Maternal
veins
Placenta
Maternal portion
of placenta
Umbilical cord
Chorionic villus
containing fetal
capillaries
Fetal portion of
placenta (chorion)
Maternal blood
pools
Uterus
Figure 46.16
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Fetal arteriole
Fetal venule
Umbilical cord
Umbilical arteries
Umbilical vein
• The first trimester is the main period of
organogenesis
– The development of the body organs
(a) 5 weeks. Limb buds, eyes, the (b) 14 weeks. Growth and
heart, the liver, and rudiments
development of the offspring,
of all other organs have started
now called a fetus, continue
to develop in the embryo, which
during the second trimester.
is only about 1 cm long.
This fetus is about 6 cm long.
Figure 46.17a–c
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
(c) 20 weeks. By the end of the
second trimester (at 24 weeks),
the fetus grows to about 30 cm
in length.
Second Trimester
• During the second trimester
– The fetus grows and is very active
– The mother may feel fetal movements
– The uterus grows enough for the pregnancy to
become obvious
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Third Trimester
• During the third trimester
– The fetus continues to grow and fills the
available space within the embryonic
membranes
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• A complex interplay of local regulators and
hormones
– Induces and regulates labor, the process by
which childbirth occurs
Oxytocin
from
ovaries
from fetus
and mother's
posterior pituitary
Induces oxytocin
receptors on uterus
Stimulates uterus
to contract
Stimulates
placenta to make
Prostaglandins
Figure 46.18
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Stimulate more
contractions
of uterus
Positive feedback
Estrogen
• Birth, or parturition
– Is brought about by a series of strong, rhythmic
uterine contractions
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• The process of labor has three stages
Placenta
Umbilical
cord
Uterus
Cervix
1
Dilation of the cervix
2
Expulsion: delivery of the infant
Uterus
Placenta
(detaching)
Umbilical
cord
Figure 46.19
3
Delivery of the placenta
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
The Mother’s Immune Tolerance of the Embryo and Fetus
• A woman’s acceptance of her “foreign”
offspring
– Is not fully understood
– May be due to the suppression of the immune
response in her uterus
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Contraception and Abortion
• Contraception, the deliberate prevention of
pregnancy
– Can be achieved in a number of ways
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Some contraceptive methods
– Prevent the release of mature eggs and sperm
from gonads
– Prevent fertilization by keeping sperm and egg
apart
– Prevent implantation of an embryo
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Mechanisms of some contraceptive methods
Female
Male
Method
Event
Event
Production of
viable sperm
Method
Production of
viable oocytes
Vasectomy
Ovulation
Sperm transport
down male
duct system
Abstinence
Combination
birth control
pill (or injection,
patch, or
vaginal ring)
Abstinence
Condom
Coitus
interruptus
(very high
failure rate)
Sperm
deposited
in vagina
Capture of the
oocyte by the
oviduct
Tubal ligation
Sperm
movement
through
female
reproductive
tract
Transport
of oocyte in
oviduct
Spermicides;
diaphragm;
cervical cap;
progestin alone
(minipill, implant,
or injection)
Meeting of sperm and oocyte
in oviduct
Union of sperm and egg
Morning-after
pill (MAP)
Progestin alone
Implantation of blastocyst
in properly prepared
endometrium
Figure 46.20
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Birth
Modern Reproductive Technology
• Recent scientific and technological advances
– Have made it possible to deal with many
reproductive problems
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Amniocentesis and chorionic villus sampling
– Are invasive techniques in which amniotic fluid
or fetal cells are obtained for genetic analysis
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
• Noninvasive procedures
– Usually use ultrasound imaging to detect fetal
condition
Head
Head
Body
Figure 46.21
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
Body
• Modern technology
– Can help infertile couples by in vitro fertilization
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings