Download Ch. 46 Lecture 46_Lecture_2014

LECTURE PRESENTATIONS
For CAMPBELL BIOLOGY, NINTH EDITION
Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson
Chapter 46
Animal Reproduction
Lectures by
Erin Barley
Kathleen Fitzpatrick
© 2011 Pearson Education, Inc.
Figure 46.1
Big Ideas (Unity and Diversity of Life)
• 1.B.1: Organisms share many conserved core processes
and features that evolved and are widely distributed
among organisms today.
– All animals reproduce (either sexually or asexually). This ensures
the continuation of the species over time.
– Consider pros and cons to both asexual and sexual reproduction
strategies (See Figure 46.3)
© 2011 Pearson Education, Inc.
Big Ideas (Dynamic Homeostasis)
• 2.A.1: All living systems require constant input of free
energy.
• Reproduction and rearing of offspring require input of free energy
beyond that used tor maintenance and growth.
• Different organisms use various strategies to achieve this:
• Seasonal reproduction in animals (estrus); see Menstrual Versus Estrous
Cycles (p. 1010)
© 2011 Pearson Education, Inc.
Big Ideas (Dynamic Homeostasis)
• 2.C.1: Organisms use feedback mechanisms to maintain
their internal environments and respond to external
environmental changes.
– Reproductive cycle of human female: understand how various
hormones inhibit or stimulate ovulation; refer to Figure 46.13
– Testosterone and inhibin (negative) (see Figure 46.14)
• Spermatogenesis
– Oxytocin (positive) (see Figure 46.18)
• Lactation and labor
© 2011 Pearson Education, Inc.
Big Ideas (Dynamic Homeostasis)
• 2.E.2: In animals, internal and external signals regulate a
variety of physiological responses that synchronize with
environmental cycles and cues.
• Estrous (see Reproductive Cycles on p. 998)
• 2.E.3: Timing and coordination of behavior are regulated
by various mechanisms and are important in natural
selection.
• Behaviors are triggered by environmental cues and are vital to
reproduction, natural selection, and survival.
• Estrous (see Reproductive Cycles on p. 998)
© 2011 Pearson Education, Inc.
Big Ideas (Dynamic Homeostasis)
• 3.A.2: Meiosis, a reduction division, followed by
fertilization ensures genetic diversity in sexually
reproducing organisms.
– Meiosis occurs in testes, ovaries leading to the production of
unique haploid gametes; refer to Figure 13.7
– Fertilization restores the diploid number in the zygote. Be familiar
with the haploid-diploid life cycle; refer to Figure 13.6
© 2011 Pearson Education, Inc.
Big Ideas (Dynamic Homeostasis)
• 3.A.3: The chromosomal basis of inheritance provides an
understanding of the pattern of passage (transmission) of
genes from parent to offspring
– Many ethical, social and medical issues surround human genetic
disorders.
• Reproduction issues; refer to Modern Reproductive Technologies (pp. 10171018)
© 2011 Pearson Education, Inc.
Big Ideas (Dynamic Homeostasis)
• 3.C.2: Biological systems have multiple processes that
increase genetic variation.
• Sexual reproduction in eukaryotes involves meiosis
• gamete formation
• crossing over
• independent assortment of chromosomes, etc.  genetic variation;
refer to Figure 13.9
© 2011 Pearson Education, Inc.
Big Ideas (Dynamic Homeostasis)
• 3.D.2: Cells communicate with each other through direct
contact with other cells or from a distance via chemical
signaling.
– Pheromones trigger sexual reproduction and developmental
pathways; refer to Chemoreceptors (pp. 1088-89)
© 2011 Pearson Education, Inc.
Big Ideas (Dynamic Homeostasis)
• 3.E.1: Individuals can act on information and
communicate it to others.
– Behaviors: Courtship/mating & parent/offspring interactions
(S.A.M.E.)
© 2011 Pearson Education, Inc.
Big Ideas (Complex Properties)
• 4.A.4 a): Organisms exhibit complex properties due to interactions
between their constituent parts
– Circulatory, endocrine, reproductive systems
• 4.A.4 b): Interactions and coordination between systems provide
essential biological activities
– Circulatory, endocrine, reproductive systems
• 4.B.2 a.2): Within multicellular organisms, specialization of organs
contributes to the overall functioning of the organism
– Circulatory, endocrine, reproductive systems
© 2011 Pearson Education, Inc.
Big Ideas (Complex Properties)
• 4.B.3) Interactions between and within populations influence
patterns of species distribution and abundance.
• mutualism, competition
© 2011 Pearson Education, Inc.
Big Ideas (Complex Properties)
• Figure 47.8: Arrangement of all three (triploblastic)
germ layers
• Ectoderm, Mesoderm, Endoderm
• Figure 47.2: Focus on embryonic development stages
• Fertilization, cleavage, gastrulation, organogenesis
• Figure 47.7: Cleavage of frog embryo
• Fertilization, cleavage, gastrulation, organogenesis
• Figure 47.10: Gastrulation in frog embryo
•
Fertilization, cleavage, gastrulation, organogenesis
© 2011 Pearson Education, Inc.
Mix & Match Review: Ch. 46.1-2
1.
2.
3.
4.
Fission
Fusion
Egg
Hermaphroditism
1.
2.
3.
4.
Fertilization
Parthenogenesis
Clone
Asexual
1.
2.
3.
4.
Internal fertilization
_____________
Genetic variation
Gamete
Concept 46.1: Both asexual and sexual
reproduction occur in the animal kingdom
• Sexual reproduction is the creation of an
offspring by fusion of a male gamete (sperm) and
female gamete (egg) to form a zygote
• Asexual reproduction is creation of offspring
without the fusion of egg and sperm
© 2011 Pearson Education, Inc.
Mechanisms of Asexual Reproduction
• Many invertebrates reproduce asexually by
fission, separation of a parent into two or more
individuals of about the same size
© 2011 Pearson Education, Inc.
Figure 46.2
• In budding, new individuals arise from outgrowths
of existing ones
• Fragmentation is breaking of the body into pieces,
some or all of which develop into adults
• Fragmentation must be accompanied by
regeneration, regrowth of lost body parts
• Parthenogenesis is the development of a new
individual from an unfertilized egg
© 2011 Pearson Education, Inc.
Sexual Reproduction: An Evolutionary
Enigma
• Sexual females have half as many daughters as
asexual females; this is the “twofold cost” of
sexual reproduction
• Despite this, almost all eukaryotic species
reproduce sexually
© 2011 Pearson Education, Inc.
Figure 46.3-1
Sexual reproduction
Asexual reproduction
Female
Generation 1
Female
Figure 46.3-2
Sexual reproduction
Asexual reproduction
Female
Generation 1
Female
Generation 2
Male
Figure 46.3-3
Sexual reproduction
Asexual reproduction
Female
Generation 1
Female
Generation 2
Male
Generation 3
Figure 46.3-4
Sexual reproduction
Asexual reproduction
Female
Generation 1
Female
Generation 2
Male
Generation 3
Generation 4
• Sexual reproduction results in genetic
recombination, which provides potential
advantages
– An increase in variation in offspring, providing an
increase in the reproductive success of parents in
changing environments
– An increase in the rate of adaptation
– A shuffling of genes and the elimination of harmful
genes from a population
© 2011 Pearson Education, Inc.
Reproductive Cycles
• Ovulation is the release of mature eggs at the
midpoint of a female cycle
• Most animals exhibit reproductive cycles related to
changing seasons
• Reproductive cycles are controlled by hormones
and environmental cues
• Because seasonal temperature is often an
important cue in reproduction, climate change can
decrease reproductive success
© 2011 Pearson Education, Inc.
Figure 46.4
• Some organisms can reproduce sexually or
asexually, depending on conditions
• Several genera of fishes, amphibians, and lizards
reproduce only by a complex form of
parthenogenesis that involves the doubling of
chromosomes after meiosis
• Asexual whiptail lizards are descended from a
sexual species, and females still exhibit mating
behaviors
© 2011 Pearson Education, Inc.
Figure 46.5
Ovary
size
(a) A. uniparens females
Hormone
level
Ovulation
Estradiol
Ovulation
Progesterone
Behavior
Time
Female
Male- Female
like
(b) The sexual behavior of A. uniparens is
correlated with the cycle of ovulation.
Malelike
Figure 46.5a
(a) A. uniparens females
Ovary
size
Figure 46.5b
Hormone
level
Ovulation
Estradiol
Ovulation
Progesterone
Behavior
Time
Female
Male- Female
like
(b) The sexual behavior of A. uniparens is
correlated with the cycle of ovulation.
Malelike
Variation in Patterns of Sexual
Reproduction
• For many animals, finding a partner for sexual
reproduction may be challenging
• One solution is hermaphroditism, in which each
individual has male and female reproductive
systems
• Two hermaphrodites can mate, and some
hermaphrodites can self-fertilize
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• Individuals of some species undergo sex reversals
• Some species exhibit male to female reversal (for
example, certain oysters), while others exhibit
female to male reversal (for example, a coral reef
fish)
© 2011 Pearson Education, Inc.
Concept 46.2: Fertilization depends on
mechanisms that bring together sperm
and eggs of the same species
• The mechanisms of fertilization, the union of egg
and sperm, play an important part in sexual
reproduction
• In external fertilization, eggs shed by the female
are fertilized by sperm in the external environment
© 2011 Pearson Education, Inc.
Video: Hydra Releasing Sperm
© 2011 Pearson Education, Inc.
• In internal fertilization, sperm are deposited in or
near the female reproductive tract, and fertilization
occurs within the tract
• Internal fertilization requires behavioral
interactions and compatible copulatory organs
• All fertilization requires critical timing, often
mediated by environmental cues, pheromones,
and/or courtship behavior
© 2011 Pearson Education, Inc.
Figure 46.6
Ensuring the Survival of Offspring
• Internal fertilization is typically associated with
production of fewer gametes but the survival of a
higher fraction of zygotes
• Internal fertilization is also often associated with
mechanisms to provide protection of embryos and
parental care of young
© 2011 Pearson Education, Inc.
• The embryos of some terrestrial animals develop
in eggs with calcium- and protein-containing shells
and several internal membranes
• Some other animals retain the embryo, which
develops inside the female
• In many animals, parental care helps ensure
survival of offspring
© 2011 Pearson Education, Inc.
Figure 46.7
Gamete Production and Delivery
• To reproduce sexually, animals must produce
gametes
• In most species individuals have gonads, organs
that produce gametes
• Some simple systems do not have gonads, but
gametes form from undifferentiated tissue
• More elaborate systems include sets of accessory
tubes and glands that carry, nourish, and protect
gametes and developing embryos
© 2011 Pearson Education, Inc.
• Most insects have separate sexes with complex
reproductive systems
• In many insects, the female has a spermatheca in
which sperm is stored during copulation
© 2011 Pearson Education, Inc.
Figure 46.8
Accessory
gland
Ejaculatory
duct
Penis and
claspers
(a) Male fruit fly
Ovary
Testis
Oviduct
Spermatheca
Vas
deferens
Seminal
vesicle
Accessory
gland
(b) Female fruit fly
Uterus
Vulva
Figure 46.8a
Accessory
gland
Ejaculatory
duct
Penis and
claspers
(a) Male fruit fly
Testis
Vas
deferens
Seminal
vesicle
Figure 46.8b
Ovary
Oviduct
Spermatheca
Accessory
gland
(b) Female fruit fly
Uterus
Vulva
• A cloaca is a common opening between the
external environment and the digestive, excretory,
and reproductive systems
• A cloaca is common in nonmammalian
vertebrates; mammals usually have a separate
opening to the digestive tract
© 2011 Pearson Education, Inc.
• Monogamy is relatively rare among animals
• Males and/or females of some species have
evolved mechanisms to decrease the chance of
their mate mating with another individual
• Females can sometimes influence the relative
reproductive success of their mates
© 2011 Pearson Education, Inc.
Figure 46.9
Percentage of females
lacking sperm in spermatheca
RESULTS
30
20
10
0
Control; Remated to Remated to Remated to
not
wild-type “no-sperm” “no-ejaculate”
remated
males
males
males
Concept 46.3: Reproductive organs
produce and transport gametes
• The following section focuses on the human
reproductive system
© 2011 Pearson Education, Inc.
Female Reproductive Anatomy
• The female external reproductive structures
include the clitoris and 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
© 2011 Pearson Education, Inc.
Animation: Female Reproductive Anatomy
Right-click slide / select “Play”
© 2011 Pearson Education, Inc.
Figure 46.10
Oviduct
Ovary
Uterus
(Urinary bladder)
(Pubic bone)
(Rectum)
Cervix
Vagina
Urethra
Body
Clitoris
Glans
Prepuce
Labia minora
Labia majora
Major vestibular
(Bartholin’s) gland
Vaginal opening
Ovaries
Oviduct
Follicles
Corpus luteum
Uterus
Uterine wall
Endometrium
Cervix
Vagina
Figure 46.10a
Oviduct
Ovary
Uterus
(Urinary bladder)
(Pubic bone)
(Rectum)
Cervix
Vagina
Urethra
Major vestibular
(Bartholin’s) gland
Vaginal opening
Body
Clitoris
Glans
Prepuce
Labia minora
Labia majora
Figure 46.10b
Ovaries
Oviduct
Follicles
Corpus luteum
Uterus
Uterine wall
Endometrium
Cervix
Vagina
Ovaries
• The female gonads, the ovaries, lie in the
abdominal cavity
• Each ovary contains many follicles, which consist
of a partially developed egg, called an oocyte,
surrounded by support cells
• Once a month, an oocyte develops into an ovum
(egg) by the process of oogenesis
© 2011 Pearson Education, Inc.
• Ovulation expels an egg cell from the follicle, the
cells of which produce estradiol prior to ovulation
• The remaining follicular tissue grows within the
ovary, forming a mass called the corpus luteum
• The corpus luteum secretes estradiol and
progesterone that helps to maintain pregnancy
• If the egg is not fertilized, the corpus luteum
degenerates
© 2011 Pearson Education, Inc.
Oviducts and Uterus
• The egg cell travels from the ovary to the uterus
via an oviduct, or fallopian tube
• Cilia in the oviduct convey the egg to the uterus,
also called the womb
• The uterus lining, the endometrium, has many
blood vessels
• The uterus narrows at the cervix, then opens into
the vagina
© 2011 Pearson Education, Inc.
Vagina and Vulva
• The vagina is a thin-walled chamber that is the
repository for sperm during copulation and serves
as the birth canal
• The vagina opens to the outside at the vulva,
which consists of the labia majora, labia minora,
hymen, and clitoris
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• The clitoris has a head called a glans covered by
the prepuce
• The vagina, labia minora, and clitoris are rich with
blood vessels; the clitoris also has many nerve
endings
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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
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Male Reproductive Anatomy
• The male’s external reproductive organs are the
scrotum and penis
• Internal organs are the gonads, which produce
sperm and hormones, and accessory glands
© 2011 Pearson Education, Inc.
Animation: Male Reproductive Anatomy
Right-click slide / select “Play”
© 2011 Pearson Education, Inc.
Figure 46.11
Seminal
vesicle
(behind
bladder)
(Urinary bladder)
Prostate gland
Bulbourethral gland
Urethra
Scrotum
Erectile tissue of penis
Vas deferens
Epididymis
Testis
(Urinary bladder)
Seminal vesicle
(Urinary duct)
(Rectum)
Vas deferens
(Pubic bone)
Ejaculatory duct
Prostate gland
Bulbourethral gland
Erectile
tissue
Urethra
Vas deferens
Epididymis
Testis
Scrotum
Glans
Prepuce
Penis
Figure 46.11a
Seminal
vesicle
(behind
bladder)
(Urinary bladder)
Prostate gland
Bulbourethral gland
Urethra
Scrotum
Erectile tissue of penis
Vas deferens
Epididymis
Testis
Figure 46.11b
(Urinary bladder)
Seminal vesicle
(Urinary duct)
(Rectum)
Vas deferens
Ejaculatory duct
Prostate gland
Bulbourethral gland
(Pubic bone)
Vas deferens
Epididymis
Testis
Scrotum
Erectile
tissue
Urethra
Glans
Prepuce
Penis
Testes
• The male gonads, or testes, consist of highly
coiled tubes surrounded by connective tissue
• Sperm form in these seminiferous tubules
• Leydig cells produce hormones and are scattered
between the tubules
• Production of normal sperm cannot occur at the
body temperatures of most mammals
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• The testes of many mammals are held outside the
abdominal cavity in the scrotum, where the
temperature is lower than in the abdominal cavity
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Ducts
• From the seminiferous tubules of a testis, sperm
pass into the coiled tubules of the epididymis
• During ejaculation, sperm are propelled through
the muscular vas deferens and the ejaculatory
duct, and then exit the penis through the urethra
© 2011 Pearson Education, Inc.
Accessory Glands
• Semen is composed of sperm plus secretions
from three sets of accessory glands
• The two seminal vesicles contribute about 60%
of the total volume of semen
• The prostate gland secretes its products directly
into the urethra through several small ducts
• The bulbourethral glands secrete a clear mucus
before ejaculation that neutralizes acidic urine
remaining in the urethra
© 2011 Pearson Education, Inc.
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
• The head of the penis has a thinner skin covering
than the shaft and is more sensitive to stimulation
© 2011 Pearson Education, Inc.
Gametogenesis
• Gametogenesis, the production of gametes,
differs in male and female, reflecting the distinct
structure and function of their gametes
• Sperm are small and motile and must pass from
male to female
• Eggs are larger and carry out their function within
the female
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• Spermatogenesis, the development of sperm, is
continuous and prolific (millions of sperm are
produced per day; each sperm takes about 7
weeks to develop
• Oogenesis, the development of a mature egg, is a
prolonged process
• Immature eggs form in the female embryo but do
not complete their development until years or
decades later
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• Spermatogenesis differs from oogenesis in three
ways
– All four products of meiosis develop into sperm
while only one of the four becomes an egg
– Spermatogenesis occurs throughout adolescence
and adulthood
– Sperm are produced continuously without the
prolonged interruptions in oogenesis
© 2011 Pearson Education, Inc.
Figure 46.12a
Epididymis
Seminiferous tubule
Testis
Primordial germ cell in embryo
Cross section of
seminiferous tubule
Mitotic divisions
Spermatogonial
stem cell
2n
Mitotic divisions
Sertoli cell
nucleus
Spermatogonium
2n
Mitotic divisions
Primary spermatocyte
2n
Meiosis I
Secondary spermatocyte
Lumen of
seminiferous tubule
Neck
Tail
Plasma
membrane
n
n
Meiosis II
Spermatids
(two stages)
Early
spermatid
n
n
n
n
Differentiation
(Sertoli cells
provide nutrients)
Midpiece Head
Acrosome
Nucleus
Mitochondria
Sperm cell
n
n
n
n
Figure 46.12aa
Epididymis Seminiferous
Sertoli cell
tubule
nucleus
Spermatogonium
Primary
spermatocyte
Testis
Cross section of
seminiferous tubule
Secondary
spermatocyte
Spermatids
(two stages)
Lumen of
seminiferous tubule
Sperm cell
Figure 46.12ab
Primordial germ cell in embryo
Mitotic divisions
2n
Spermatogonial stem cell
Mitotic divisions
Spermatogonium
2n
Mitotic divisions
Primary spermatocyte
2n
Meiosis I
Secondary spermatocyte
n
n
Meiosis II
Early
spermatid
Sperm cell
n
n
n
n
Differentiation
(Sertoli cells
provide nutrients)
n
n
n
n
Figure 46.12ac
Neck
Plasma
membrane
Tail
Midpiece Head
Acrosome
Nucleus
Mitochondria
Figure 46.12b
Primary
oocyte
within
follicle
Ovary
Primordial germ cell
Growing
follicle
In embryo
Mitotic divisions
2n
Oogonium
Mitotic divisions
Primary oocyte
(present at birth), arrested
in prophase of meiosis I
2n
First
polar
body
Completion of meiosis I
and onset of meiosis II
n
n
Secondary oocyte,
arrested at metaphase of
meiosis II
Ovulation, sperm entry
Mature follicle
Ruptured
follicle
Ovulated
secondary
oocyte
Completion of meiosis II
Corpus luteum
Second
polar
n
body
n
Fertilized egg
Degenerating
corpus luteum
Figure 46.12ba
Ovary
Primary
oocyte
within
follicle
Growing
follicle
Ruptured
follicle
Ovulated
secondary
oocyte
Corpus luteum
Mature follicle
Degenerating
corpus luteum
Figure 46.12bb
Primordial germ cell
Mitotic divisions
2n
In embryo
Oogonium
Mitotic divisions
Primary oocyte
(present at birth), arrested
in prophase of meiosis I
2n
First
polar
body
Completion of meiosis I
and onset of meiosis II
n
n
Secondary oocyte,
arrested at metaphase of
meiosis II
Ovulation, sperm entry
Completion of meiosis II
Second
polar
n
body
n
Fertilized egg
Concept 46.4: The interplay of tropic and
sex hormones regulates mammalian
reproduction
• Human reproduction is coordinated by hormones
from the hypothalamus, anterior pituitary, and
gonads
• Gonadotropin-releasing hormone (GnRH) is
secreted by the hypothalamus and directs the
release of FSH and LH from the anterior pituitary
• FSH and LH regulate processes in the gonads and
the production of sex hormones
© 2011 Pearson Education, Inc.
• Sex hormones serve many functions in addition to
gamete production, including sexual behavior and
the development of primary and secondary sex
characteristics
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Hormonal Control of the Female
Reproductive Cycles
• In females, the secretion of hormones and the
reproductive events they regulate are cyclic
• Prior to ovulation, the endometrium thickens with
blood vessels in preparation for embryo
implantation
• If an embryo does not implant in the endometrium,
the endometrium is shed in a process called
menstruation
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• Hormones closely link the two cycles of female
reproduction
– Changes in the uterus define the menstrual cycle
(also called the uterine cycle)
– Changes in the ovaries define the ovarian cycle
© 2011 Pearson Education, Inc.
(a)
Control by hypothalamus
GnRH
1
Anterior pituitary
2
(b)
Inhibited by combination of
estradiol and progesterone

Hypothalamus
FSH

Stimulated by high levels
of estradiol

Inhibited by low levels of
estradiol
LH
Pituitary gonadotropins
in blood
6
LH
FSH
(c)
Ovarian cycle
7
Growing follicle
Maturing
follicle
8
Follicular phase
Corpus
luteum
Ovulation
Ovarian hormones
in blood
Degenerating
corpus luteum
Luteal phase
Estradiol secreted
by growing follicle in
increasing amounts
4
(d)
LH surge triggers
ovulation
FSH and LH stimulate
follicle to grow
3
Progesterone and
estradiol secreted
by corpus luteum
Peak causes
LH surge
(see 6 )
5
10
9
Estradiol
Progesterone
Progesterone and estradiol promote thickening
of endometrium
Estradiol level
very low
Uterine (menstrual) cycle
(e)
Endometrium
Menstrual flow phase Proliferative phase
Days
Figure 46.13
0
5
10
14 15
Secretory phase
20
25
28
Figure 46.13a
(a)
Control by hypothalamus
Hypothalamus

GnRH

Inhibited by combination of
estradiol and progesterone
Stimulated by high levels
of estradiol

Inhibited by low levels of
estradiol
1
Anterior pituitary
2
FSH
LH
Figure 46.13b
(b)
Pituitary gonadotropins
in blood
6
LH
FSH
3
Ovarian cycle
7
Growing follicle
Maturing
follicle
(c)
Days
FSH and LH stimulate
follicle to grow
8
Follicular phase
0
5
LH surge triggers
ovulation
10
Corpus
luteum
Ovulation
14 15
Degenerating
corpus luteum
Luteal phase
20
25
28
Figure 46.13c
Estradiol secreted
by growing follicle in
increasing amounts
4
Ovarian hormones
in blood
(d)
Progesterone and
estradiol secreted
by corpus luteum
Peak causes
LH surge
(see 6 )
5
10
9
Estradiol
Progesterone
Progesterone and estradiol promote thickening
of endometrium
Estradiol level
very low
Uterine (menstrual) cycle
(e)
Endometrium
(e)
Days
Menstrual flow phase
0
5
Proliferative phase
10
14 15
Secretory phase
20
25
28
The Ovarian Cycle
• The sequential release of GnRH then FSH and LH
stimulates follicle growth
• Follicle growth and an increase in the hormone
estradiol characterize the follicular phase of the
ovarian cycle
• The follicular phase ends at ovulation, and the
secondary oocyte is released
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Animation: Ovulation
Right-click slide / select “Play”
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• Following ovulation, the follicular tissue left behind
transforms into the corpus luteum; this is the
luteal phase
• The corpus luteum disintegrates, and ovarian
steroid hormones decrease
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Animation: Post Ovulation
Right-click slide / select “Play”
© 2011 Pearson Education, Inc.
The Uterine (Menstrual) Cycle
• Hormones coordinate the uterine cycle with the
ovarian cycle
– Thickening of the endometrium during the
proliferative phase coordinates with the follicular
phase
– Secretion of nutrients during the secretory phase
coordinates with the luteal phase
– Shedding of the endometrium during the
menstrual flow phase coordinates with the
growth of new ovarian follicles
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• A new cycle begins if no embryo implants in the
endometrium
• Cells of the uterine lining can sometimes migrate
to an abnormal, or ectopic, location
• Swelling of these cells in response to hormone
stimulation results in a disorder called
endometriosis
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Menopause
• After about 500 cycles, human females undergo
menopause, the cessation of ovulation and
menstruation
• Menopause is very unusual among animals
• Menopause might have evolved to allow a mother
to provide better care for her children and
grandchildren
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Menstrual Versus Estrous Cycles
• Menstrual cycles are characteristic only of humans
and some other primates
– The endometrium is shed from the uterus in a
bleeding called menstruation
– Sexual receptivity is not limited to a time frame
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• Estrous cycles are characteristic of most
mammals
– The endometrium is reabsorbed by the uterus
– Sexual receptivity is limited to a “heat” period
– The length and frequency of estrus cycles vary
from species to species
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Hormonal Control of the Male Reproductive
System
• FSH promotes the activity of Sertoli cells, which
nourish developing sperm
• LH regulates Leydig cells, which secrete
testosterone and other androgens, which in turn
promote spermatogenesis
© 2011 Pearson Education, Inc.
Animation: Male Hormones
Right-click slide / select “Play”
© 2011 Pearson Education, Inc.
Figure 46.14

Hypothalamus
GnRH


FSH
LH
Leydig cells
Sertoli cells
Inhibin
Spermatogenesis
Testis
Testosterone
Negative feedback
Negative feedback
Anterior pituitary
• Testosterone regulates the production of GnRH,
FSH, and LH through negative feedback
mechanisms
• Sertoli cells secrete the hormone inhibin, which
reduces FSH secretion from the anterior pituitary
© 2011 Pearson Education, Inc.
Human Sexual Response
• Two reactions predominate in both sexes
– Vasocongestion, the filling of tissue with blood
– Myotonia, increased muscle tension
• The sexual response cycle has four phases:
excitement, plateau, orgasm, and resolution
• Excitement prepares the penis and vagina for
coitus (sexual intercourse)
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• Direct stimulation of genitalia maintains the
plateau phase and prepares the vagina for receipt
of sperm
• Orgasm is characterized by rhythmic contractions
of reproductive structures
– In males, semen is first released into the urethra
and then ejaculated from the urethra
– In females, the uterus and outer vagina contract
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• During the resolution phase, organs return to their
normal state and muscles relax
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Concept 46.5: In placental mammals, an
embryo develops fully within the mother’s
uterus
• An egg develops into an embryo in a series of
predictable events
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Conception, Embryonic Development, and
Birth
• Conception, fertilization of an egg by a sperm,
occurs in the oviduct
• The resulting zygote begins to divide by mitosis in
a process called cleavage
• Division of cells gives rise to a blastocyst, a ball
of cells with a central cavity
© 2011 Pearson Education, Inc.
Figure 46.15
3
Cleavage
4
Cleavage
continues
5
Implantation
Ovary
2
Fertilization
Uterus
1
Ovulation
(a) From ovulation to implantation
Endometrium
Endometrium
Inner cell
mass
Cavity
Blastocyst
(b) Implantation of blastocyst
Trophoblast
• After blastocyst formation, the embryo implants
into the endometrium
• The embryo releases human chorionic
gonadotropin (hCG), which prevents
menstruation
• Pregnancy, or gestation, is the condition of
carrying one or more embryos in the uterus
• Duration of pregnancy in other species correlates
with body size and maturity of the young at birth
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• Pregnancies can terminate spontaneously due to
chromosomal or developmental abnormalities
• An ectopic pregnancy occurs when a fertilized egg
begins to develop in the fallopian tube
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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
• During implantation, the endometrium grows over
the blastocyst
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• During its first 2 to 4 weeks, the embryo obtains
nutrients directly from the endometrium
• Meanwhile, the outer layer of the blastocyst, called
the trophoblast, mingles with the endometrium
and eventually forms the placenta
• Blood from the embryo travels to the placenta
through arteries of the umbilical cord and returns
via the umbilical vein
© 2011 Pearson Education, Inc.
Figure 46.16
Maternal
arteries
Placenta
Umbilical
cord
Maternal
veins
Maternal
portion of
placenta
Chorionic
villus,
containing
fetal
capillaries
Fetal
portion of
placenta
(chorion)
Maternal
blood pool
Uterus
Fetal arteriole
Fetal venule
Umbilical cord
Umbilical
arteries
Umbilical vein
• Splitting of the embryo during the first month of
development results in genetically identical twins
• Release and fertilization of two eggs result in
fraternal and genetically distinct twins
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• The first trimester is the main period of
organogenesis, development of the body organs
• All the major structures are present by 8 weeks,
and the embryo is called a fetus
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• Changes occur in the mother
–
–
–
–
–
Mucus plug to protect against infection
Growth of the placenta and uterus
Cessation of ovulation and the menstrual cycle
Breast enlargement
Nausea is also very common
© 2011 Pearson Education, Inc.
Figure 46.17
(a) 5 weeks
(b) 14 weeks
(c) 20 weeks
Figure 46.17a
(a) 5 weeks
Figure 46.17b
(b) 14 weeks
Figure 46.17c
(c) 20 weeks
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
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Third Trimester
• During the third trimester, the fetus grows and fills
the space within the embryonic membranes
• A complex interplay of local regulators and
hormones induces and regulates labor, the
process by which childbirth occurs
© 2011 Pearson Education, Inc.
Figure 46.18
from
ovaries
Oxytocin

from fetus
and mother’s
posterior pituitary
Activates oxytocin
receptors on uterus
Stimulates uterus
to contract
Stimulates
placenta to make
Prostaglandins
Stimulate more
contractions
of uterus

Positive feedback
Estradiol
• Labor typically has three stages
– Thinning and opening of the cervix, or dilation
– Expulsion or delivery of the baby
– Delivery of the placenta
© 2011 Pearson Education, Inc.
Figure 46.19
Placenta
Umbilical cord
Uterus
Cervix
1 Dilation of the cervix
2 Expulsion: delivery of the infant
Uterus
Placenta
(detaching)
Umbilical cord
3 Delivery of the placenta
Figure 46.19a
Placenta
Umbilical cord
Uterus
Cervix
1 Dilation of the cervix
Figure 46.19b
2 Expulsion: delivery of the infant
Figure 46.19c
Uterus
Placenta
(detaching)
Umbilical
cord
3 Delivery of the placenta
• Delivery of the baby and placenta is brought about
by a series of strong, rhythmic uterine contractions
• Lactation, the production of milk, is unique to
mammals
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Maternal Immune Tolerance of the Embryo
and Fetus
• A woman’s acceptance of her “foreign” offspring is
not fully understood
• It may be due to suppression of the immune
response in her uterus
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Contraception and Abortion
• Contraception, the deliberate prevention of
pregnancy, can be achieved in a number of ways
• Contraceptive methods fall into three categories
– Preventing release of eggs and sperm
– Keeping sperm and egg apart
– Preventing implantation of an embryo
© 2011 Pearson Education, Inc.
• A health-care provider should be consulted for
complete information on the choice and risks of
contraception methods
© 2011 Pearson Education, Inc.
Figure 46.20
Female
Male
Method
Event
Production
of sperm
Event
Production of
primary oocytes
Vasectomy
Oocyte
Sperm transport
development
down male
and ovulation
duct system
Abstinence
Condom
Coitus
interruptus
(very high
failure rate)
Method
Combination
birth control
pill (or injection,
patch, or
vaginal ring)
Abstinence
Female condom
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;
progestin alone
(as minipill
or injection)
Meeting of sperm and oocyte
in oviduct
Union of sperm and egg
Implantation of blastocyst
in endometrium
Morning-after
pill; intrauterine
device (IUD)
Figure 46.20a
Female
Male
Method
Event
Production
of sperm
Event
Production of
primary oocytes
Vasectomy
Oocyte
Sperm transport
development
down male
duct system and ovulation
Abstinence
Condom
Coitus
interruptus
(very high
failure rate)
Method
Combination
birth control
pill (or injection,
patch, or
vaginal ring)
Abstinence
Female condom
Sperm
deposited
in vagina
Capture of the
oocyte by the
oviduct
Tubal ligation
Spermicides;
diaphragm;
progestin alone
(as minipill
or injection)
Figure 46.20b
Male
Method
Female
Event
Sperm
movement
through female
reproductive
tract
Event
Transport
of oocyte in
oviduct
Method
Meeting of sperm and oocyte
in oviduct
Union of sperm and egg
Implantation of blastocyst
in endometrium
Morning-after
pill; intrauterine
device (IUD)
• The rhythm method, or natural family planning,
is to refrain from intercourse when conception is
most likely; it has a pregnancy rate of 10–20%
• Coitus interruptus, the withdrawal of the penis
before ejaculation, is unreliable
• Barrier methods block fertilization with a
pregnancy rate of less than 10%
– A condom fits over the penis
– A diaphragm is inserted into the vagina before
intercourse
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• Intrauterine devices (IUDs) are inserted into the
uterus and interfere with fertilization and
implantation; the pregnancy rate is less than 1%
• Female birth control pills are hormonal
contraceptives with a pregnancy rate of less than
1%
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• Sterilization is permanent and prevents the
release of gametes
– Tubal ligation ties off the oviducts
– Vasectomy ties off the vas deferens
• Abortion is the termination of a pregnancy
• Spontaneous abortion, or miscarriage, occurs in
up to one-third of all pregnancies
• The drug RU486 results in an abortion within the
first 7 weeks of a pregnancy
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Modern Reproductive Technologies
• Recent advances are addressing reproductive
problems
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Detecting Disorders During Pregnancy
• Amniocentesis and chorionic villus sampling are
invasive techniques in which amniotic fluid or fetal
cells are obtained for genetic analysis
• Noninvasive procedures usually use ultrasound
imaging to detect fetal condition
• Genetic testing of the fetus poses ethical
questions and can present parents with difficult
decisions
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Treating Infertility
• Modern technology can provide infertile couples
with assisted reproductive technologies
• In vitro fertilization (IVF) mixes eggs with sperm
in culture dishes and returns the embryo to the
uterus at the 8-cell stage
• Sperm are injected directly into an egg in a type of
IVF called intracytoplasmic sperm injection
(ICSI)
© 2011 Pearson Education, Inc.
Video: Ultrasound of Human Fetus 1
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Video: Ultrasound of Human Fetus 2
© 2011 Pearson Education, Inc.
Figure 46.UN01
Human gametogenesis
Oogenesis
Spermatogenesis
Primary
spermatocyte
2n
2n
Primary
oocyte
n
n
Secondary
spermatocytes
n
n
n
n
n
Spermatids
n
n
n
n
Sperm
n
n
n
Polar body
Secondary
oocyte
Polar body
Fertilized egg
Figure 46.UN02