Lecture%2019%20Placentation%20and%20Maternal%20Recognition%20of%20Pregnancy

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Lecture 19Placentation and Maternal Recognition
of Pregnancy

• Animal Science 434
• John J. Parrish

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Blastulation
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Hatching

• Bovine
• 9 - 11 days
• Equine, Ovine
• 7 - 8 days
• Porcine
• 6 days

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Conceptus Growth

• Cow
• Day 15, 1-2 mm
• Day 18-19, 10-20 cm

Occurs in cow, pig and sheep
Mare remains spherical!
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Development of Porcine Conceptuses from Day 10 to
12
5 mm Spherical
10 mm Spherical
Inner Cell Mass
15 mm Tubular
150 mm Filamentous
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Elongated Day 15 Porcine Conceptus
Embryo
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Uterine Location of Elongating Ruminant Blastocyst
Corpus Luteum
Bovine and Ovine
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Pig Intrauterine Migration

Day 5
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Pig Intrauterine Migration
Day 7
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Pig Intrauterine Migration
Transuterine migration is rare in cow and ewe!
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Transuterine Migration in the Mare
Begins Day 10
Corpus Luteum
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Gastrulation
Trophectoderm
Inner Cell Mass
Formation of Germ Layers
Endoderm
Blastocoele Cavity
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Gastrulation
14
Gastrula
Ectoderm
Trophectoderm
Endoderm
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Gastrula
Ectoderm
Mesoderm
Extraembryonic Coelom
Yolk Sack
Trophectoderm (Chorion)
Endoderm
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Germ Layers

• Ectoderm
• CNS
• Sense organs
• Mammary glands
• Sweat glands
• Skin
• Hair
• hooves

• Mesoderm
• Circulatory
• Skeletal
• Muscle
• Reproductive tracts
• Kidneys
• Urinary ducts

• Endoderm
• Digestive
• Liver
• Lungs
• Pancreas
• Thyroid gland
• Other glands

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Placenta Formation
Embryonic Ectoderm
Amniotic Folds
Extraembryonic Ceolom
Yolk Sack
Trophectoderm
Chorion
Mesoderm
Endoderm
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Amniotic Fold
Amniotic Cavity
Allantois
Extraembryonic Ceolom
Yolk Sack
Chorion
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Amnionic Cavity
Amnion
Uterine Lumen
Allantois
Yolk Sack
Chorion
Extraembryonic Ceolom
Carnuncle
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Amniotic Cavity
Chorion
Amnion
Allantois Cavity
Yolk Sack
Allantochorion (Chorioallantois)
Cotyledon
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Placental Membranes

• Yolk Sack
• In birds to nourish embryo
• In mammal atrophies but source of blood cells
  and primordial germ cells
• Amnion
• Non-vascular, fluid filled
• Fluid produced by fetus
• Protective cushion
• Ruptures at birth (not breaking of water)

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Placental Membranes (cont.)

• Allantois
• Blood vessels
• Fuses with chorion
• Allantochorion or chorioallantois
• Brings blood vessels to chorion
• Chorion
• Outermost membrane
• Attachment to mother

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Maternal Recognition of Pregnancy
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Luteal Regression
PGF2a (Bovine, Ovine, Porcine)
PGF2a (Equine)
No Uterine Factor (human)
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CL Status
CA

• Mechanisms
• CL Regression
• Luteolytic
• No CL support
• CL Maintenance
• Antiluteolytic
• Block PGF2a effects
• Luteotrophic
• Stimulate progesterone production by CL

() Uterine PGF2a
CL
Filamentous Embryo ()
Maintained
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Recognition of Pregnancy

• Conceptus Secretions
• Proteins
• Steroids

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Recognition of Pregnancy in Bovine and Ovine

• Conceptus Secretions
• Interferons
• oIFN-t
• bIFN-t

• Mechanism
• Antiluteolytic
• Inhibit oxytocin receptor synthesis
• Inhibit PGF2a synthesis

• Critical Days
• Bovine - 16 to 17
• Ovine - 12 to 13

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Recognition of Pregnancy in the Porcine
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Recognition of Pregnancy in the Porcine

• Conceptus Secretions
• Estradiol

Critical Days 11 to 12

• Mechanism
• Antiluteolytic
• Redirect PGF2a
• Requires 2 embryos per horn

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Recognition of Pregnancy in the Mare

• Conceptus Secretion
• ?

Critical Days 10 to 14
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Recognition of Pregnancy in the Human

• Conceptus Secretes
• HCG

• Mechanism
• luteotrophic

• Critical Days
• 8 to 12

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Recognition of Pregnancy in Rodents

• Estrous cycle - 4 days
• Mating induces prolactin
• Maintenance of CL
• Psuedopregnancy
• Not Pregnant
• Prl i after day 7
• PGF h day 11
• Estrus by day 17
• Pregnant
• RPL h after day 7, h P4
• PGF h day 11
• RPL protects CL from PGF

• Luteotrophic
• Antiluteolytic

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Recognition of Pregnancy
INF-t RPL HCG Estradiol

• Conceptus Secretions
• Proteins
• Steroids

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Implantantion
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Time of Implantation
Attachment to Uterus
Species
Beginning
Completion
pig 13 24 cow 22 40 sheep 15 28 mare 24 -
40 95 - 100 human 7 - 8 30
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Type of Implantation

• Superficial
• Chorion lies opposed to uterine wall
• Farm animals
• Eccentric
• Chorionic sack in a uterine fold
• Rodent
• Interstitial
• Embryo digests part of uterine wall
• human

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Degree of Tissue Loss at Parturition

• Deciduate
• Eccentric, interstitial
• Rodent, human
• Indeciduate or Nondeciduate
• Superficial
• Farm animals

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Cotelydonary Placenta
Cow
Ewe
70 - 120
90 - 100
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Cotelydonary Placenta
Cow
Ewe
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Placental Attachment in Ruminant
Binucleate Cell
Chorion
Migrate and fuse with uterine epithelium
Uterine Epithelium
Syncytium
Capillary
Fusion of Binucleate cells and uterine epithelium
(multinucleate)
Stroma
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Day 23 Migration of Bicnucleate Cells and
Formation of Syncytium
Binucleate Cell
Endometrial Stroma
Multinucleated Cells in Uterine Epithelium
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Binuclear Giant Cells

• 20 of fetal placenta
• Invade endometrium
• Source
• Placental lactogen
• Pregnancy specific protein B

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Placental Lactogens (Protein Hormones)
Prolactin-like activity
Stimulates Milk Synthesis
Not Present in Pig and Mare

• May regulate maternal metabolism to facilitate
  fetal growth
• High levels in the last 1/3 of gestation.
• High levels facilitate higher milk production.
• Dairy cows have higher blood concentrations than
  beef cows

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Pregnancy Specific Protein B

• Unique to ruminants
• Function uncertain
• Has been used to detect pregnancy
• Cattle, sheep, deer
• Can be used to detect pregnancy in cows after day
  25

• Not early pregnancy factor!!!

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Diffuse Placenta
Horse
Pig
Microcotyledons
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Microcotelydons
Increase placental surface area
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Endometrial Cups in Mare

• From both trophoblast and endometrium
• 5 to 10
• Form between days 35 to 60
• Produce equine chorionic gonadotropin (eCG, PMSG)
• Sloughed off after day 60

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Zonary Placenta(bitch, queen)
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Discoid Placenta(human)
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Cell Layers Separating Maternal and Fetal Blood
Maternal
Fetal
Capillary
Capillary
Endothelium
Endothelium
Connective Tissue
Connective Tissue
Chorionic Epithelium
Endometrial Epithelium
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Histological Classification
Tissues epithelial- syndesmo- endothelial- hemo- h
emo- chorial chorial chorial chorial endothelial
Maternal endothelium - - conn.
tissue - - - epithelium - - - - Fetal
epithelium - conn. tissue -
endothelium Species pig ruminant dog h
uman rat horse cat rabbit ruminant
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Important!!!!

• In all cases, fetal and maternal blood does not
  mix.