Download Chap 28b - Dr. Jerry Cronin

PowerPoint® Lecture Slides
prepared by
Barbara Heard,
Atlantic Cape Community
College
CHAPTER
28
Pregnancy
and Human
Development:
Part B
© Annie Leibovitz/Contact Press Images
© 2013 Pearson Education, Inc.
Organogenesis
• Gastrulation sets stage for organogenesis
– Formation of body organs and systems
• At eighth week
– All organ systems recognizable
– End of embryonic period
© 2013 Pearson Education, Inc.
Organogenesis
• Embryo begins as flat plate 
• Cylindrical body resembling three stacked
sheets of paper folding laterally into tube,
and at both ends
© 2013 Pearson Education, Inc.
Figure 28.10 Folding of the embryonic body, lateral views.
Head
Tail
Amnion
Yolk sac
Ectoderm
Mesoderm
Endoderm
Trilaminar
embryonic
disc
Future gut
(digestive
tube)
Lateral
fold
Somites
(seen
through
ectoderm)
Tail
fold
Head
fold
Yolk sac
Neural
tube
Notochord
Primitive
gut
Hindgut
© 2013 Pearson Education, Inc.
Yolk
sac
Foregut
Specialization of Endoderm
• Primitive gut formed from endodermal
folding
– Forms epithelial lining of GI tract
– Organs of GI tract become apparent, and oral
and anal openings perforate
• Mucosal lining of respiratory tract forms
from pharyngeal endoderm (foregut)
• Glands arise further along tract
© 2013 Pearson Education, Inc.
Figure 28.10a Folding of the embryonic body, lateral views.
Head
Tail
Amnion
Yolk sac
Ectoderm
Mesoderm
Endoderm
© 2013 Pearson Education, Inc.
Trilaminar
embryonic
disc
Figure 28.10b Folding of the embryonic body, lateral views.
Lateral
fold
© 2013 Pearson Education, Inc.
Future gut
(digestive
tube)
Figure 28.10c Folding of the embryonic body, lateral views.
Somites
(seen
through
ectoderm)
Tail
fold
Head
fold
Yolk sac
© 2013 Pearson Education, Inc.
Figure 28.10d Folding of the embryonic body, lateral views.
Neural
tube
Notochord
Primitive
gut
Hindgut
© 2013 Pearson Education, Inc.
Yolk
sac
Foregut
Figure 28.11 Endodermal differentiation.
Pharynx
Parathyroid
glands and
thymus
Thyroid
gland
Esophagus
Trachea
Connection
to yolk sac
Right and
left lungs
Stomach
Liver
Umbilical
cord
Pancreas
Gallbladder
Small intestine
Allantois
Large intestine
5-week embryo
© 2013 Pearson Education, Inc.
Specialization of Ectoderm
• Neurulation
– First major event of organogenesis
– Gives rise to brain and spinal cord
– Induced by chemical signals from notochord
– Ectoderm over notochord thickens, forming
neural plate
– Neural plate folds inward as neural groove
with neural folds
© 2013 Pearson Education, Inc.
Specialization of Ectoderm
• By 22nd day, neural folds fuse into neural
tube
– Anterior end  brain; rest  spinal cord
• Neural crest cells migrate widely 
cranial, spinal, and sympathetic ganglia
and nerves; adrenal medulla; pigment
cells of skin; contribute to some
connective tissues
• Brain waves recorded by end of second
month
© 2013 Pearson Education, Inc.
Figure 28.12a Neurulation and early mesodermal differentiation.
Head
Amnion
Amniotic cavity
Left
Right
Cut
edge of
amnion
Primitive
streak
Tail
Neural plate
Ectoderm
Mesoderm
Notochord
Endoderm
Yolk sac
© 2013 Pearson Education, Inc.
17 days. The flat three-layered
embryo has completed
gastrulation. Notochord and
neural plate are present.
Figure 28.12b Neurulation and early mesodermal differentiation.
Neural
crest
Neural
groove
Neural
fold
Coelom
© 2013 Pearson Education, Inc.
Somite
Intermediate
mesoderm
20 days. The neural folds form
by folding of the neural plate, which
then deepens, producing the
neural groove. Three mesodermal
Lateral plate aggregates form on each side of
the notochord (somite,
mesoderm
intermediate mesoderm, and
lateral plate mesoderm).
Figure 28.12c Neurulation and early mesodermal differentiation.
Surface
ectoderm
Neural
crest
Neural
tube
Somite
Notochord
© 2013 Pearson Education, Inc.
22 days. The neural folds have
closed, forming the neural tube
which has detached from the
surface ectoderm and lies
between the surface ectoderm
and the notochord. Embryonic
body is beginning to undercut.
Figure 28.12d Neurulation and early mesodermal differentiation.
Neural tube
(ectoderm)
Somite
Dermatome
Myotome
Sclerotome
Kidney and gonads
(intermediate
mesoderm)
Epidermis
(ectoderm)
Gut lining
(endoderm)
Lateral plate
mesoderm
• Limb bud
• Smooth
muscle of gut
• Visceral serosa
Peritoneal cavity
(coelom)
© 2013 Pearson Education, Inc.
• Parietal serosa
• Dermis
End of week 4. Embryo
undercutting is complete. Somites
have subdivided into sclerotome,
myotome, and dermatome, which
form the vertebrae, skeletal
muscles, and dermis respectively.
Body coelom present.
Specialization of Mesoderm
• First evidence - appearance of notochord
– Eventually replaced by vertebral column
• Three mesoderm aggregates appear
lateral to notochord
– Somites, intermediate mesoderm, and double
sheets of lateral plate mesoderm
© 2013 Pearson Education, Inc.
Specialization of Mesoderm
• Somites (40 pairs) each have three
functional parts
– Sclerotome cells - produce vertebra and rib
at each level
– Dermatome cells - form dermis of skin on
dorsal part of body
– Myotome cells - form skeletal muscles of
neck, trunk, and limbs (via limb buds)
© 2013 Pearson Education, Inc.
Specialization of Mesoderm
• Intermediate mesoderm forms gonads
and kidneys
• Lateral plate mesoderm consists of
somatic and splanchnic mesoderm
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Specialization of the Mesoderm
• Somatic mesoderm forms
– Dermis of skin in ventral region
– Parietal serosa of ventral body cavity
– Most tissues of limbs
• Splanchnic mesoderm forms
– Heart and blood vessels
– Most connective tissues of body
– ~ Entire wall of digestive & respiratory organs
© 2013 Pearson Education, Inc.
Specialization of the Mesoderm
• At end of embryonic period
– Bones have begun to ossify; skeletal muscles
well formed, contracting; metanephric kidneys
developing; gonads formed
– Lungs, digestive organs attaining final shape
and body position
– Blood delivery to/from placenta constant &
efficient
– Heart and liver bulge on ventral surface
© 2013 Pearson Education, Inc.
Figure 28.12a Neurulation and early mesodermal differentiation.
Head
Amnion
Amniotic cavity
Left
Right
Cut
edge of
amnion
Primitive
streak
Tail
Neural plate
Ectoderm
Mesoderm
Notochord
Endoderm
Yolk sac
© 2013 Pearson Education, Inc.
17 days. The flat three-layered
embryo has completed
gastrulation. Notochord and
neural plate are present.
Figure 28.12b Neurulation and early mesodermal differentiation.
Neural
crest
Neural
groove
Neural
fold
Coelom
© 2013 Pearson Education, Inc.
Somite
Intermediate
mesoderm
20 days. The neural folds form
by folding of the neural plate, which
then deepens, producing the
neural groove. Three mesodermal
Lateral plate aggregates form on each side of
the notochord (somite,
mesoderm
intermediate mesoderm, and
lateral plate mesoderm).
Figure 28.12c Neurulation and early mesodermal differentiation.
Surface
ectoderm
Neural
crest
Neural
tube
Somite
Notochord
© 2013 Pearson Education, Inc.
22 days. The neural folds have
closed, forming the neural tube
which has detached from the
surface ectoderm and lies
between the surface ectoderm
and the notochord. Embryonic
body is beginning to undercut.
Figure 28.12d Neurulation and early mesodermal differentiation.
Neural tube
(ectoderm)
Somite
Dermatome
Myotome
Sclerotome
Kidney and gonads
(intermediate
mesoderm)
Epidermis
(ectoderm)
Gut lining
(endoderm)
Lateral plate
mesoderm
• Limb bud
• Smooth
muscle of gut
• Visceral serosa
Peritoneal cavity
(coelom)
© 2013 Pearson Education, Inc.
• Parietal serosa
• Dermis
End of week 4. Embryo
undercutting is complete. Somites
have subdivided into sclerotome,
myotome, and dermatome, which
form the vertebrae, skeletal
muscles, and dermis respectively.
Body coelom present.
Figure 28.13 Flowchart showing major derivatives of the embryonic germ layers.
Epiblast
ECTODERM
MESODERM
Notochord
Somite
Intermediate
mesoderm
ENDODERM
Lateral plate
mesoderm
Somatic
mesoderm
• Epidermis, hair,
nails, glands of skin
• Brain and spinal
cord
• Neural crest and
derivatives (e.g.,
cranial, spinal, and
sympathetic
ganglia and
associated nerves;
chromaffin cells of
the adrenal
medulla; pigment
cells of the skin)
© 2013 Pearson Education, Inc.
Nucleus
pulposus of
intervertebral
discs
• Sclerotome:
vertebrae and
ribs
• Dermatome:
dermis of
dorsal body
region
• Myotome:
trunk and limb
musculature
• Kidneys
• Parietal serosa
• Gonads
• Dermis of ventral
body region
• Connective
tissues of limbs
(bones, joints,
and ligaments)
Splanchnic
mesoderm
• Wall of
digestive and
respiratory
tracts (except
epithelial
lining)
• Visceral serosa
• Heart
• Blood vessels
Epithelial lining
and glands of
digestive and
respiratory
tracts
Development of Fetal Circulation
• First blood cells arise in yolk sac
• By end of third week
– Embryo has system of paired vessels
– Two vessels forming heart have fused; bent
into "S" shape
• Heart beats by 3½ weeks
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Development of Fetal Circulation
• Unique vascular modifications
– Umbilical arteries and umbilical vein
– Three vascular shunts
• All occluded at birth
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Development of Fetal Circulation
• Vascular shunts
– Ductus venosus - bypasses liver (umbilical
vein  ductus venosus  IVC)
– Foramen ovale - opening in interatrial
septum; bypasses pulmonary circulation
– Ductus arteriosus - bypasses pulmonary
circulation (pulmonary trunk  ductus
arteriosus  aorta)
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Figure 28.14a Circulation in fetus and newborn.
Fetus
Aortic arch
Superior vena cava
Ductus arteriosus
Ligamentum arteriosum
Pulmonary artery
Pulmonary veins
Heart
Lung
Foramen ovale
Fossa ovalis
Liver
Ductus venosus
Ligamentum venosum
Hepatic portal vein
Umbilical vein
Ligamentum teres
Inferior vena cava
Umbilicus
Abdominal aorta
Common iliac artery
Umbilical arteries
Medial umbilical ligaments
Urinary bladder
Umbilical cord
Placenta
© 2013 Pearson Education, Inc.
High oxygenation
Moderate oxygenation
Low oxygenation
Very low oxygenation
Figure 28.14b Circulation in fetus and newborn.
Aortic arch
Superior vena cava
Ductus arteriosus
Newborn
Ligamentum arteriosum
Pulmonary artery
Pulmonary veins
Heart
Lung
Foramen ovale
Fossa ovalis
Liver
Ductus venosus
Ligamentum venosum
Hepatic portal vein
Umbilical vein
Ligamentum teres
Inferior vena cava
Umbilicus
Abdominal aorta
Common iliac artery
Umbilical arteries
Medial umbilical ligaments
Urinary bladder
© 2013 Pearson Education, Inc.
High oxygenation
Moderate oxygenation
Low oxygenation
Very low oxygenation
Events of Fetal Development
• Fetal period - weeks 9 through 38
• Time of rapid growth of body structures
established in embryo
© 2013 Pearson Education, Inc.
Figure 28.15a Photographs of a developing fetus.
Amniotic sac Umbilical cord Umbilical vein
Chorionic
villi
Yolk sac
Cut edge
of chorion
Embryo at week 7, about 17 mm long.
© 2013 Pearson Education, Inc.
Figure 28.15b Photographs of a developing fetus.
Fetus in month 3, about 6 cm long.
© 2013 Pearson Education, Inc.
Figure 28.15c Photographs of a developing fetus.
© 2013 Pearson Education, Inc.
Fetus late in month 5, about 19 cm long.
Table 28.1 Developmental Events of the Fetal Period (1 of 3)
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Table 28.1 Developmental Events of the Fetal Period (2 of 3)
© 2013 Pearson Education, Inc.
Table 28.1 Developmental Events of the Fetal Period (3 of 3)
© 2013 Pearson Education, Inc.
Effects of Pregnancy on the Mother:
Anatomical Changes
• Reproductive organs become engorged
with blood
– Chadwick's sign - vagina develops purplish
hue
– Breasts enlarge and areolae darken
– Pigmentation of facial skin many increase
(chloasma)
© 2013 Pearson Education, Inc.
Effects of Pregnancy: Anatomical Changes
• Uterus expands, occupying most of
abdominal cavity
– Ribs flare  thorax widens
• Lordosis occurs with change in center of
gravity
• Relaxin causes pelvic ligaments and
pubic symphysis to relax to ease birth
passage
• Weight gain of ~13 kg (28 lb)
© 2013 Pearson Education, Inc.
Effects of Pregnancy: Anatomical Changes
• Good nutrition vital
– 300 additional daily calories
• Multivitamins with folic acid reduce fetal
risk of neurological problems, e.g., spina
bifida, anencephaly, and spontaneous
preterm birth
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Figure 28.16 Relative size of the uterus before conception and during pregnancy.
Before conception
(Uterus the size of a
fist and resides
in the pelvis.)
© 2013 Pearson Education, Inc.
4 months
(Fundus of the
uterus is halfway
between the pubic
symphysis and
the umbilicus.)
7 months
(Fundus is well
above the
umbilicus.)
9 months
(Fundus
reaches the
xiphoid
process.)
Effects of Pregnancy: Metabolic Changes
• Placental hormones
– Human placental lactogen (hPL) (human
chorionic somatomammotropin (hCS))
•  maturation of breasts, fetal growth, and glucose
sparing in mother (reserving glucose for fetus)
• Parathyroid hormone and vitamin D levels
high throughout pregnancy  adequate
calcium for fetal bone mineralization
© 2013 Pearson Education, Inc.
Effects of Pregnancy: Physiological
Changes
• GI tract
– Morning sickness believed due to elevated
levels of hCG, estrogen and progesterone
– Heartburn and constipation are common
• Urinary system
–  Urine production due to  maternal
metabolism and fetal wastes
– Frequent, urgent urination; stress
incontinence may occur as bladder
compressed
© 2013 Pearson Education, Inc.
Effects of Pregnancy: Physiological
Changes
• Respiratory system
– Estrogens may cause nasal edema and
congestion
– Tidal volume increases
– Dyspnea (difficult breathing) may occur later
in pregnancy
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Effects of Pregnancy: Physiological
Changes
• Cardiovascular system
– Blood volume increases 25–40%
• Safeguards against blood loss during childbirth
– Cardiac output rises as much as 35-40%
• Propels greater volume around body
– Venous return from lower limbs may be
impaired, resulting in varicose veins
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Homeostatic Imbalance
• Preeclampsia
– Insufficient placental blood supply  fetus
starved of oxygen
– Woman  edematous, hypertensive,
proteinuria
– Believed due to immunological abnormalities
• Correlated with number of fetal cells that enter
maternal circulation
© 2013 Pearson Education, Inc.
Parturition
• Giving birth to baby
• Labor
– Events that expel infant from uterus
• Increased production of surfactant protein
A (SP-A) in weeks before delivery 
inflammatory response in cervix 
softening in preparation for labor
© 2013 Pearson Education, Inc.
Initiation of Labor
• Fetus determines own birth date
• During last few weeks of pregnancy
– Fetal secretion of cortisol stimulates placenta
to secrete more estrogen
• Causes production of oxytocin receptors by
myometrium
• Causes formation of gap junctions between uterine
smooth muscle cells
• Antagonizes calming effects of progesterone,
leading to Braxton Hicks contractions in uterus
© 2013 Pearson Education, Inc.
Initiation of Labor
• Surfactant protein A (SP-A) from fetal
lungs causes softening of cervix
• Fetal oxytocin causes placenta to
produce prostaglandins
• Oxytocin and prostaglandins - powerful
uterine muscle stimulants
– Due especially to prostaglandins, contractions
 more frequent and vigorous
– Anti-prostaglandins contraindicated during
labor
© 2013 Pearson Education, Inc.
Initiation of Labor
• Increasing cervical distension
– Activates hypothalamus, causing oxytocin
release from posterior pituitary
– Positive feedback mechanism occurs
• Greater distension of cervix  more oxytocin
release  greater contractile force  greater
distension of cervix  etc.
© 2013 Pearson Education, Inc.
Figure 28.17 Hormonal induction of labor.
Start
Estrogen
Oxytocin
from
placenta
from fetus
and mother's
posterior pituitary
Induces oxytocin
receptors on uterus
Stimulates uterus
to contract
Stimulates
placenta to release (+)
Prostaglandins
Stimulate more
vigorous contractions
of uterus
© 2013 Pearson Education, Inc.
Positive feedback
(+)
Stages of Labor: Dilation Stage
• From labor's onset to fully dilated cervix (10 cm)
• Longest stage of labor - 6–12 hours or more
• Initial weak contractions:
– 15–30 minutes apart, 10–30 seconds long
– Become more vigorous and rapid
• Cervix effaces and dilates fully to 10 cm
• Amnion ruptures, releasing amniotic fluid
• Engagement occurs - head enters true pelvis
© 2013 Pearson Education, Inc.
Figure 28.18 Parturition.
1a Early dilation.
Baby’s head engaged;
widest dimension Is
along left-right axis.
1b Late dilation.
Baby’s head rotates so
widest dimension is in
anteroposterior axis
(of pelvic outlet). Dilation
nearly complete
Umbilical cord
Placenta
Uterus
Cervix
Vagina
Slide 1
Pubic
symphysis
Sacrum
2 Expulsion.
Baby’s head extends
as it is delivered
3 Placental stage.
After baby is delivered,
the placenta detaches
and is removed.
© 2013 Pearson Education, Inc.
Perineum
Uterus
Placenta (detaching)
Umbilical cord
Figure 28.18 Parturition.
1a Early dilation.
Baby’s head engaged;
widest dimension Is
along left-right axis.
© 2013 Pearson Education, Inc.
Umbilical cord
Placenta
Uterus
Cervix
Vagina
Slide 2
Figure 28.18 Parturition.
1a Early dilation.
Baby’s head engaged;
widest dimension Is
along left-right axis.
1b Late dilation.
Baby’s head rotates so
widest dimension is in
anteroposterior axis
(of pelvic outlet). Dilation
nearly complete
© 2013 Pearson Education, Inc.
Umbilical cord
Placenta
Uterus
Cervix
Vagina
Pubic
symphysis
Sacrum
Slide 3
Stages of Labor: Expulsion Stage
• From full dilation to delivery of infant
• Strong contractions every 2–3 minutes,
about 1 minute long
• Urge to push increases (in absence of
local anesthesia)
• Crowning occurs when largest dimension
of head distends vulva
– Episiotomy may be done to reduce tearing
© 2013 Pearson Education, Inc.
Figure 28.18 Parturition.
1a Early dilation.
Baby’s head engaged;
widest dimension Is
along left-right axis.
1b Late dilation.
Baby’s head rotates so
widest dimension is in
anteroposterior axis
(of pelvic outlet). Dilation
nearly complete
Umbilical cord
Placenta
Uterus
Cervix
Vagina
Pubic
symphysis
Sacrum
2 Expulsion.
Baby’s head extends
as it is delivered
Perineum
© 2013 Pearson Education, Inc.
Slide 4
Stages of Labor: Expulsion Stage
• Vertex position – head-first
– Skull dilates cervix; early suctioning allows
breathing prior to complete delivery
• Breech position – buttock-first
– Delivery more difficult; often forceps required,
or C-section (delivery through abdominal and
uterine wall incision)
© 2013 Pearson Education, Inc.
Figure 28.18 Parturition.
1a Early dilation.
Baby’s head engaged;
widest dimension Is
along left-right axis.
1b Late dilation.
Baby’s head rotates so
widest dimension is in
anteroposterior axis
(of pelvic outlet). Dilation
nearly complete
Umbilical cord
Placenta
Uterus
Cervix
Vagina
Slide 5
Pubic
symphysis
Sacrum
2 Expulsion.
Baby’s head extends
as it is delivered
3 Placental stage.
After baby is delivered,
the placenta detaches
and is removed.
© 2013 Pearson Education, Inc.
Perineum
Uterus
Placenta (detaching)
Umbilical cord
Stages of Labor: Placental Stage
• Strong contractions continue, causing
detachment of placenta and compression
of uterine blood vessels
– Limit bleeding; cause placental detachment
• Delivery of afterbirth (placenta and
membranes) occurs ~30 minutes after
birth
• All placenta fragments must be removed
to prevent postpartum bleeding
© 2013 Pearson Education, Inc.
Adjustments of the Infant to Extrauterine
Life
• Neonatal period - four-week period immediately
after birth
• Physical status assessed 1–5 minutes after birth
– Apgar score - 0–2 points each for
• Heart rate
• Respiration
• Color
• Muscle tone
• Reflexes
– Score of 8–10 - healthy
© 2013 Pearson Education, Inc.
First Breath
•  CO2  central acidosis  stimulates
respiratory control centers to trigger first
inspiration
– Requires tremendous effort – airways tiny;
lungs collapsed
– Surfactant in alveolar fluid helps reduce
surface tension
• Respiratory rate ~45 per minute first two
weeks, then declines
© 2013 Pearson Education, Inc.
First Breath
• Keeping lungs inflated difficult for
premature infant (< 2500 g, or 5.5 pounds,
at birth)
– Surfactant production in last months of
prenatal life
– Preemies usually on respiratory assistance
until lungs mature
© 2013 Pearson Education, Inc.
Transitional Period
• Unstable period lasting 6–8 hours after
birth
– Alternating periods of activity and sleep
– Vital signs may be irregular during activity
– Baby gags frequently as regurgitates mucus
and debris
• Stabilizes with waking periods occurring
every 3–4 hours
© 2013 Pearson Education, Inc.
Occlusion of Fetal Blood Vessels
• Umbilical arteries and vein constrict and
become fibrosed
• Proximal umbilical arteries  superior
vesical arteries to urinary bladder
• Distal umbilical arteries  medial
umbilical ligaments
© 2013 Pearson Education, Inc.
Occlusion of Fetal Blood Vessels
• Umbilical vein becomes round ligament
of liver (ligamentum teres)
• Ductus venosus  ligamentum
venosum about 30 minutes after birth
• Pressure changes from infant breathing
cause pulmonary shunts to close
– Foramen ovale  fossa ovalis up to a year
after birth
– Ductus arteriosus  ligamentum
arteriosum about 30 minutes after birth
© 2013 Pearson Education, Inc.
Lactation
• Production of milk by mammary glands
• Toward end of pregnancy
– Placental estrogens, progesterone, and
human placental lactogen stimulate
hypothalamus to release prolactin-releasing
factors (PRFs) 
– Anterior pituitary releases prolactin
• 2-3 days later true milk production begins
© 2013 Pearson Education, Inc.
Lactation
• Colostrum
– Less lactose but more protein, vitamin A,
minerals than true milk; almost no fat
– Yellowish secretion rich in IgA antibodies
• IgA resistant to digestion; may protect infant
against bacterial infection; absorbed into
bloodstream for immunity
– Released first 2–3 days
– Followed by true milk production
© 2013 Pearson Education, Inc.
Lactation
• Prolactin release wanes after birth
• Lactation sustained by mechanical
stimulation of nipples - suckling
– Suckling causes afferent impulses to
hypothalamus  prolactin  stimulates milk
production for next feeding
– Hypothalamus also  oxytocin from posterior
pituitary  let-down reflex
© 2013 Pearson Education, Inc.
Figure 28.19 Milk production and the positive feedback mechanism of the milk let-down reflex.
Hypothalamus releases prolactin
releasing factors (PRF)
to portal circulation.
Start
Positive feedback
Stimulation of
mechanoreceptors in
nipples by suckling
infant sends afferent
impulses to the
hypothalamus.
Hypothalamus
sends efferent
impulses to the
posterior
pituitary where
oxytocin is stored.
Anterior pituitary
secretes prolactin
to blood.
Oxytocin is
released from the
posterior pituitary
and stimulates
myoepithelial cells
of breasts to contract.
Prolactin targets
mammary glands
of breasts.
Let-down reflex.
Milk is ejected
through ducts
of nipples.
© 2013 Pearson Education, Inc.
Milk production
Advantages of Breast Milk
• Fats and iron better absorbed; amino
acids more easily metabolized, compared
with cow's milk
• Beneficial chemicals
– IgA, complement, lysozyme, interferon, and
lactoperoxidase (protect from infections)
– Interleukins and prostaglandins prevent
overzealous inflammatory responses
– Glycoprotein deters ulcer-causing bacterium
from attaching to stomach mucosa
© 2013 Pearson Education, Inc.
Advantages of Breast Milk
• Natural laxative effect helps eliminate bile-rich
meconium, helping to prevent physiological
jaundice
• Encourages bacterial colonization of large
intestine
• Women nursing 6 months lose bone calcium;
replaced after weaning if healthy diet
• Women may ovulate when nursing despite
inhibition of GnRH and gonadotropins
© 2013 Pearson Education, Inc.
Assisted Reproductive Technology
• Surgical removal of oocytes following
hormone stimulation
• Fertilization of oocytes
• Return of fertilized oocytes to woman's
body
• Disadvantages
– Costly, emotionally draining, painful for oocyte
donor
© 2013 Pearson Education, Inc.
Assisted Reproductive Technology
• In vitro fertilization (IVF)
– Oocytes and sperm incubated in culture
dishes for several days
– Embryos (two-cell to blastocyst stage)
transferred to uterus for possible implantation
© 2013 Pearson Education, Inc.
Assisted Reproductive Technology
• Zygote intrafallopian transfer (ZIFT)
– Fertilized oocytes transferred to uterine tubes
• Gamete intrafallopian transfer (GIFT)
– Sperm and harvested oocytes are transferred
together into the uterine tubes
• Cloning
– Legal, moral, ethical, political roadblocks
© 2013 Pearson Education, Inc.