Download Chapter 27: Reproduction and Development

BIOLOGY
CONCEPTS & CONNECTIONS
Fourth Edition
Neil A. Campbell • Jane B. Reece • Lawrence G. Mitchell • Martha R. Taylor
CHAPTER 27
Reproduction and Embryonic
Development
From PowerPoint® Lectures for Biology: Concepts & Connections
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Mating Without Males
• There are no male desert-grassland whiptail
lizards
• The species reproduces without copulation or
fertilization
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• This photo shows a ritual behavior that primes
a female to lay eggs
– The female on top behaves much like a male in
other species of whiptail lizards
• Mating behavior
seems to be an
evolutionary
leftover
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• Although the reproduction method of desertgrassland whiptails is unusual, their embryonic
development is similar to all other animal
species
• Reptiles, birds,
and mammals
have four
embryonic
membranes
Chorion
Embryo
Amnion
Allantois
Yolk
Yolk sac
Shell
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• All animal species have three stages of
embryonic development
– Mitotic cell division
– Cellular differentiation
– Formation of the body and its structures
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ASEXUAL AND SEXUAL REPRODUCTION
27.1 Sexual and asexual reproduction are both
common among animals
• Asexual reproduction
– Budding
– Fission
– Fragmentation,
accompanied by
regeneration
– Development of an
unfertilized egg
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Figure 27.1A
• Sexual reproduction
– The fission of two haploid gametes from two
parents to form a diploid zygote
Figure 27.1D
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• Rotifers can
reproduce both
asexually and sexually
“Head”
Intestine
Ovary
Eggs
• Hermaphroditism
– A single individual
has both male and
female reproductive
systems
Figure 27.1B, C
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• Advantages of asexual reproduction
– A single individual reproduces
– Many offspring are produced rapidly
• Disadvantage of asexual reproduction
– Little or no genetic variation
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• Advantages of sexual reproduction
– Increases genetic variation
– Enhances reproductive success in changing
environments
• Disadvantage of sexual reproduction
– Locating a mate
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HUMAN REPRODUCTION
27.2 Reproductive anatomy of the human female
• Ovaries
– Contain
follicles
that nurture
eggs
– Produce
sex hormones
• Oviducts
– Convey eggs
to the uterus
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Ovaries
Oviduct
Corpus luteum Follicles
Uterus
Cervix
(“neck” of uterus)
Wall of uterus
Endometrium
(lining of uterus)
Vagina
Figure 27.2A
• Uterus
– Development
of fertilized egg
– Opens into
the vagina
Ovaries
• Vagina
– Receives
penis during
intercourse
– Forms the
birth canal
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Oviduct
Corpus luteum Follicles
Uterus
Cervix
(“neck” of uterus)
Wall of uterus
Endometrium
(lining of uterus)
Vagina
Figure 27.2A
• Ovulation
– An egg cell is released from a follicle at the
surface of an ovary
– The orange mass below the ejected oocyte is part
of the ovary
Egg
cell
Figure 27.2B
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Oviduct
Ovary
Uterus
Bladder
(excretory system)
Rectum
(digestive system)
Pubic bone
Cervix
Urethra
(excretory system)
Shaft
Vagina
Glans
Bartholin’s gland
Clitoris
Prepuce
Labia minora
Labia majora
Vaginal opening
Figure 27.2C
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27.3 Reproductive anatomy of the human male
• Semen
– Sperm, which are expelled through the ducts
during ejaculation
– Glandular secretions that carry, nourish, and
protect the sperm
• Testes
– Produce sperm
– Located outside abdominal cavity within the
scrotum
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Bladder
(excretory
system)
Seminal
vesicle
(behind
bladder)
Prostate gland
Bulbourethral
gland
Urethra
Erectile tissue
of penis
Vas deferens
Scrotum
Epididymis
Testis
Glans of
penis
Figure 27.3B
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Bladder
(excretory
system)
Seminal vesicle
Rectum
(digestive system)
Pubic bone
Vas deferens
Ejaculatory
duct
Erectile tissue
of penis
Prostate gland
Urethra
Vas deferens
Bulbourethral gland
Epididymis
Testis
Scrotum
Glans of penis
Prepuce
Figure 27.3A
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• There are two stages of ejaculation
– First stage of ejaculation
Sphincter
contracts
Contractions
of vas deferens
Bladder
Urethra region here
expands and fills
with semen
Contractions
of seminal
vesicle
Contractions
of prostate
gland
Contractions
of epididymis
Sphincter
contracts
Figure 27.3C
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– Second stage of ejaculation (expulsion stage)
Sphincter remains
contracted
Semen expelled
Contractions
of muscles
around base
of penis
Contractions
of epididymis
Sphincter
relaxes
Figure 27.3C
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• Androgens stimulate sperm production
– They also maintain homeostasis by a negative
feedback mechanism that inhibits the secretion
of FSH (follicle-stimulating hormone) and LH
(luteinizing hormone)
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Stimuli from other
areas in the brain
Hypothalamus
Anterior
pituitary
FSH
Negative feedback
Releasing
hormone
LH
Androgen
production
Testis
Sperm
production
Figure 27.3D
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27.4 The formation of sperm and ova requires
meiosis
• Spermatogenesis
– Produces sperm in the male
• Oogenesis
– Produces ova in the female
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• Spermatogenesis
– Increases genetic variation
– Primary spermatocytes are produced throughout
a male’s reproductive years
– Diploid cells undergo meiosis to form four
haploid sperm
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Epididymis
Testis
Scrotum
Penis
Diploid cell
Differentiation and
onset of MEIOSIS I
Testis
Seminiferous tubule
PRIMARY SPERMATOCYTE
MEIOSIS I completed
Cross section of
seminiferous
tubule
(in prophase of MEIOSIS I)
SECONDARY SPERMATOCYTE
(haploid; double chromatids)
MEIOSIS II
Developing sperm cells
(haploid; single chromatids)
Differentiation
SPERM CELLS
(haploid)
Center of
seminiferous
tubule
Figure 27.4A
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• Oogenesis
– Most of the process occurs within the ovaries
– Lifetime supply of primary oocytes is present at
birth
– One primary oocyte matures each month to form
a secondary oocyte
– If the secondary oocyte is fertilized, it completes
meiosis and becomes a haploid ovum
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Diploid cell
In embryo
Differentiation and
onset of MEIOSIS I
PRIMARY OOCYTE,
arrested in prophase
of MEIOSIS I
Present at birth
Completion of MEIOSIS I
and onset of MEIOSIS II
SECONDARY OOCYTE,
arrested at metaphase
of MEIOSIS II;
released from ovary
First
polar body
Entry of sperm triggers
completion of MEIOSIS II
OVUM
(haploid)
Second
polar body
Figure 27.4B
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• Development of an ovarian follicle
Degenerating
corpus luteum
Start:
PRIMARY OOCYTE
within follicle
CORPUS LUTEUM
Growing
follicles
Mature follicle
SECONDARY
OOCYTE
Ovary
OVULATION
Ruptured follicle
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Figure 27.4C
27.5 Hormones synchronize cyclical changes in the
ovary and uterus
Table 27.5
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(1)
Inhibited by combination
of estrogen and
progesterone
CONTROL BY HYPOTHALAMUS
Hypothalamus
Stimulated by high
levels of estrogen
Releasing
hormone
Anterior pituitary
FSH
(2)
LH
PITUITARY HORMONES
IN BLOOD
LH peak triggers
ovulation and
corpus luteum
formation
LH
FSH
FSH
LH
Figure 27.5
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(3) OVARIAN CYCLE
Growing
follicle
Mature
follicle
Ovulation
Corpus
luteum
Degenerating
corpus
luteum
Post-ovulatory phase
Pre-ovulatory phase
Progesterone
and estrogen
Estrogen
(4) OVARIAN HORMONES
IN BLOOD
Estrogen
Progesterone
Progesterone
and estrogen
Estrogen
(5) MENSTRUAL CYCLE
Endometrium
Menstruation
Days
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Figure 27.5 (continued)
27.6 The human sexual response occurs in four
phases
• Excitement
– Sexual passion builds
– Penis and clitoris become erect
– Testes, labia, nipples swell
– Vagina secretes lubricating fluid
– Muscles of arms and legs tighten
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• Plateau
– Continuation of excitement responses
– Increase in breathing and heart rates
• Orgasm
– Rhythmic contraction of the reproductive
structures
– Extreme pleasure
– Ejaculation by the male
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• Resolution
– Reverse previous phase responses
– Structures return to normal size
– Muscles relax
– Passion subsides
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27.7 Connection: Sexual activity can transmit
disease
Table 27.7
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27.8 Connection: Contraception prevents
unwanted pregnancy
• Contraception prevents pregnancy in one of
three ways
– Blocking the
release of
gametes
– Preventing
fertilization
– Preventing
implantation
Figure 27.8
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Table 27.8
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PRINCIPLES OF EMBRYONIC DEVELOPMENT
27.9 Fertilization results in a zygote and triggers
embryonic development
• The shape of a human sperm cell is adapted to
its function
Plasma membrane
Middle
piece
Neck
Head
Tail
Mitochondrion
(spiral shape)
Nucleus
Acrosome
Figure 27.9B
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• Only one of these
sperm will penetrate
this human egg cell
to initiate
fertilization
– Fertilization is the
union of a sperm
and an egg to form a
diploid zygote
Figure 27.9A
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• Process of
fertilization
1 The sperm
approaches
the egg
2 The sperm’s
acrosomal enzymes
digest the
egg’s jelly
3 Proteins on the
coat
sperm head bind
to egg receptors
SPERM
4 The plasma membranes
of sperm and egg fuse
Sperm
head
5 The sperm
nucleus
enters
the egg
cytoplasm
Nucleus
Acrosome
Acrosomal
Plasma
membrane enzymes
6 A
fertilization
envelope
forms
Receptor protein
molecules
Plasma
membrane
Jelly
coat
Vitelline
layer
Cytoplasm
EGG CELL
Sperm
nucleus
Egg
nucleus
7 The nuclei
of sperm
and egg fuse
Zygote
nucleus
Figure 27.9C
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27.10 Cleavage produces a ball of cells from the
zygote
• Cleavage is the first major phase of embryonic
development
– It is the rapid succession of cell divisions
– It creates a multicellular embryo from the zygote
– It partitions the multicellular embryo into
developmental regions
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• Cleavage in
a sea urchin
ZYGOTE
2 cells
4 cells
8 cells
Blastocoel
Many cells
(solid ball)
Figure 27.10
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BLASTULA
(hollow ball)
Cross section
of blastula
27.11 Gastrulation produces a three-layered
embryo
• Gastrulation is the second major phase of
embryonic development
– It adds more cells to the embryo
– It sorts all cells into three distinct cell layers
– The embryo is transformed from the blastula
into the gastrula
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• The three layers produced in gastrulation
– Ectoderm, the outer layer
– Endoderm, an embryonic digestive tract
– Mesoderm, which partly fills the space between
the ectoderm and endoderm
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Animal pole
• Development of
frog gastrula
Blastocoel
1
Vegetal pole
BLASTULA
GASTRULATION
2
Blastopore
forming
Blastopore
forming
Blastocoel
shrinking
Archenteron
3
Archenteron
Ectoderm
Mesoderm
Endoderm
4
Yolk plug
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Yolk plug
GASTRULA
Figure 27.11C
27.12 Organs start to form after gastrulation
• Embryonic tissue layers begin to differentiate
into specific tissues and organ systems
• In chordates
– the notochord develops from the mesoderm
– the neural tube develops from the ectoderm
• The neural tube becomes the brain and spinal
cord
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Neural Neural
fold
plate
Neural
fold
Neural
plate
Notochord
Ectoderm
Mesoderm
Endoderm
Archenteron
Neural folds
Outer layer
of ectoderm
Neural tube
Figure 27.12A, B
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Neural tube
• Somites are
blocks of
mesoderm that
will give rise to
segmental
structures
• The body cavity,
or coelom, also
develops from
the mesoderm
Notochord
Somite
Coelom
Archenteron
(digestive cavity)
Somites
Tail bud
Eye
Figure 27.12C
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Table 27.12
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• The tissues and organs of a tadpole emerge
from cells of the ectoderm, mesoderm, and
endoderm
Figure 27.12D
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27.13 Changes in cell shape, cell migration, and
programmed cell death give form to the
developing animal
Ectoderm
• Tissues and organs
take shape in a
developing embryo
as a result of
– cell shape changes
– cell migration
Figure 27.13A
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– programmed
cell death
(apoptosis)
Cell
suicide
Dead cell
engulfed and
digested by
adjacent
cell
Figure 27.13B
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27.14 Embryonic induction initiates organ
formation
• Induction is the mechanism by which one group
of cells influences the development of tissues
and organs from ectoderm, endoderm, and
mesoderm
– Adjacent cells and cell layers use chemical
signals to influence differentiation
– Chemical signals turn on a set of genes whose
expression makes the receiving cells differentiate
into a specific tissue
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• Induction during egg development
Lens ectoderm
Future
brain
Optic cup
Cornea
Lens
Optic
vesicle
Future
retina
Optic
stalk
1
2
3
4
Figure 27.14
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27.15 Pattern formation organizes the animal body
• Pattern formation is the emergence of a body
form with structures in their correct relative
positions
– It involves the response of genes to spatial
variations of chemicals in the embryo
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• Wing development
ANTERIOR
Bird
embryo
VENTRAL
Normal wing
Limb bud
DISTAL
Limb bud develops
DORSAL
PROXIMAL
POSTERIOR
Figure 27.15A
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• Pattern-forming zone
Donor
limb
bud
Graft of cells
from patternforming
zone
Host
limb
bud
Wing with
duplication
Graft
Host limb bud develops
Donor cells
Host patternforming zone
Figure 27.15B
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HUMAN DEVELOPMENT
27.16 The embryo and placenta take shape during
the first month of pregnancy
• Gestation is pregnancy
– It begins at conception and continues until birth
– Human gestation is 266 days
(38 weeks or 9 months)
– Mouse gestation is 1 month
– Elephant gestation is 22 months
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• Human development begins with fertilization
in the oviduct
Cleavage starts
Fertilization
of ovum
Ovary
Oviduct
Secondary
oocyte
Blastocyst
(implanted)
Ovulation
Endometrium
Uterus
Figure 27.16A
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• Cleavage produces
a blastocyst
ENDOMETRIUM
Inner cell mass
– A blastocyst is a
fluid-filled cavity
– The inner cells of
the blastocyst
form the baby
– The outer cells
form the embryo
trophoblast
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Cavity
Trophoblast
Figure 27.16B
• The trophoblast secretes enzymes to enable the
blastocyst to implant in the uterine wall
ENDOMETRIUM
Blood vessel
(maternal)
Future embryo
Multiplying cells
of trophoblast
Future
yolk sac
Trophoblast
UTERINE CAVITY
Figure 27.16C
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• Gastrulation occurs and organs develop from
the ectoderm, endoderm, and mesoderm
Amniotic
cavity
Amnion
Mesoderm
cells
Chorion
Yolk sac
Figure 27.16D
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• Meanwhile, the four embryonic membranes
develop
– Amnion
– Chorion
– Yolk sac
Chorion
Chorionic villi
Amnion
EMBRYO:
Allantois
Ectoderm
Mesoderm
– Allantois
Endoderm
Yolk sac
Figure 27.16E
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• The embryo floats in the fluid-filled amniotic
cavity, while the chorion and embryonic
mesoderm form the embryo’s part of the
placenta
Placenta
• The placenta’s
chorionic villi
absorb food
and oxygen
from the
mother’s
blood
Mother’s blood
vessels
Allantois
Yolk sac
Amniotic
cavity
Amnion
Embryo
Chorion
Chorionic
villi
Figure 27.16F
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• The placenta allows for a variety of substances
to pass from mother to fetus
– Protective antibodies
– German measles virus
– HIV
– Drugs (prescription and nonprescription)
– Alcohol
– Chemicals in tobacco smoke
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27.17 Human development from conception to
birth is divided into three trimesters
• First trimester
– First three months
– The most rapid changes occur during the first
trimester
Figure 27.17A, B
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• Second trimester
– Increase in size of fetus
– General refinement of human features
Figure 27.17C, D
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• Third trimester
– Growth and
preparation for
birth
Figure 27.17E
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27.18 Childbirth is hormonally induced and occurs
in three stages
• Hormonal changes induce birth
– Labor is controlled by a positive feedback
mechanism
– Estrogen released from the ovaries increases the
sensitivity of the uterus to oxytocin
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• Oxytocin is a powerful stimulant for the smooth
muscles of the uterus
– Oxytocin also stimulates the placenta to make
prostoglandins that stimulate the uterine
muscles to contract even more
• Uterine contractions stimulate the release of
more and more oxytocin and prostoglandins
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from
ovaries
OXYTOCIN
From fetus
and pituitary
Induces oxytocin
receptors on uterus
Stimulates uterus
to contract
Positive feedback
ESTROGEN
Stimulates
placenta to make
PROSTAGLANDINS
Stimulates more
contractions
of uterus
Figure 27.18A
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• There are three
stages of labor
Placenta
• Dilation of the cervix
is the first stage
Umbilical
cord
Uterus
– Cervix reaches full
dilation at 10cm
– Longest stage of
labor (6-12 hours or
longer)
Cervix
1
Dilation of the cervix
Figure 27.18B, part 1
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• Expulsion is the second stage
– Period from full
dilation of the cervix to
delivery of the infant
– Uterine contractions
occur every 2-3 minutes
– Mother feels urge to
push down with her
abdominal muscles
– Infant is forced down
and out of uterus and
vagina within a period
of 20 minutes
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2
Expulsion: delivery of the infant
Figure 27.18B, part 2
• The delivery of the
placenta is the
final stage of labor
Uterus
– Usually occurs
within 15 minutes
after the birth of the
baby
Placenta
(detaching)
Umbilical
cord
3
Delivery of the placenta
Figure 27.18B, part 3
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• Hormones continue to be important after the
baby and placenta are delivered
– Decreasing progesterone and estrogen levels
allow the uterus to return to its pre-pregnancy
state
– Oxytocin and prolactin stimulate milk secretion
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27.19 Connection: Reproductive technology
increases our reproductive options
• Reproductive technology
– Hormone therapy can increase sperm or egg
production
– Surgery can correct blocked oviducts
• Assisted reproductive
technology
– In vitro fertilization
(IVF)
• Surrogate motherhood
Figure 27.19
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