Title: Lecture 19 Placentation and Maternal Recognition of Pregnancy
1Lecture 19Placentation and Maternal Recognition
of Pregnancy
- Animal Science 434
- John J. Parrish
2Blastulation
Gap Junctions
Inner Cell Mass
Zona Pellucida
Trophectoderm
Tight Junctions
3Hatching
- Bovine
- 9 - 11 days
- Equine, Ovine
- 7 - 8 days
- Porcine
- 6 days
4Conceptus Growth
- Cow
- Day 15, 1-2 mm
- Day 18-19, 10-20 cm
Occurs in cow, pig and sheep
Embryonic Area
Spherical
Tubular
Elongating Trophoblast
Mare remains spherical!
Filamentous
5Development of Porcine Conceptuses from Day 10 to
12
5 mm Spherical
10 mm Spherical
Inner Cell Mass
15 mm Tubular
150 mm Filamentous
6Elongated Day 15 Porcine Conceptus
Embryo
7Uterine Location of Elongating Ruminant Blastocyst
Corpus Luteum
Bovine and Ovine
8Pig Intrauterine Migration
Day 5
9Pig Intrauterine Migration
Day 7
10Pig Intrauterine Migration
Transuterine migration is rare in cow and ewe!
11Trans-uterine Migration in the Mare
Begins Day 10
Fixation on day 15 - 16
Fixation can occur in either horn!
Corpus Luteum
12Gastrulation
Trophectoderm
Inner Cell Mass
Formation of Germ Layers
Endoderm
Blastocoele Cavity
13Gastrulation
Endoderm
Yolk Sack
14Gastrulation
Endoderm
Yolk Sack
15Gastrula
Ectoderm
Trophectoderm
Endoderm
16Gastrula
Ectoderm
Mesoderm
Extraembryonic Coelom
Yolk Sack
Trophectoderm (Chorion)
Endoderm
17Germ 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
18Placenta Formation
Embryonic Ectoderm
Amniotic Folds
Extraembryonic Ceolom
Yolk Sack
Trophectoderm
Chorion
Mesoderm
Endoderm
19Amniotic Fold
Amniotic Cavity
Allantois
Extraembryonic Ceolom
Yolk Sack
Chorion
20Amnionic Cavity
Amnion
Uterine Lumen
Allantois
Yolk Sack
Chorion
Extraembryonic Ceolom
Carnuncle
21Amniotic Cavity
Chorion
Amnion
Allantois Cavity
Yolk Sack
Allantochorion (Chorioallantois)
Cotyledon
22Placental 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)
23Placental Membranes (cont.)
- Allantois
- Blood vessels
- Fuses with chorion
- Allantochorion or chorioallantois
- Brings blood vessels to chorion
- Chorion
- Outermost membrane
- Attachment to mother
24Maternal Recognition of Pregnancy
25Luteal Regression
PGF2a (Bovine, Ovine, Porcine)
PGF2a (Equine)
No Uterine Factor (human)
26CL 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
27Recognition of Pregnancy
- Conceptus Secretions
- Proteins
- Steroids
28Recognition 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
29Recognition of Pregnancy in the Porcine
30Recognition of Pregnancy in the Porcine
PGF2a
PGF2a
31Recognition of Pregnancy in the Porcine
- Conceptus Secretions
- Estradiol
Critical Days 11 to 12
- Mechanism
- Antiluteolytic
- Redirect PGF2a
- Requires 2 embryos per horn
32Recognition of Pregnancy in the Mare
Critical Days 10 to 14
33Recognition of Pregnancy in the Human
34Recognition of Pregnancy
INF-t HCG Estradiol
- Conceptus Secretions
- Proteins
- Steroids
35Dog and Cat
- CL does not regress if not pregnant
- no uterine effect
- Psuedopregnancy
- CL last similar length as in pregnancy
36Implantation
37Time 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
38Type 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
39Degree of Tissue Loss at Parturition
- Deciduate
- Eccentric, interstitial
- Rodent, human
- Indeciduate or Nondeciduate
- Superficial
- Farm animals
40Shape or Distribution of Chorionic Villi
- Cotelydonary - cow, sheep
- Diffuse - pig, horse
- Zonary - dog, cat
- Discoid - human
41Cotelydonary Placenta
Cow
Convex
Ewe
Cotelydon (Chorion)
Caruncle
70 - 120
90 - 100
Endometrium
42Cotelydonary Placenta
Cow
Ewe
Placentome
43Placental 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
44Day 23 Migration of Bicnucleate Cells and
Formation of Syncytium
Binucleate Cell
Endometrial Stroma
Multinucleated Cells in Uterine Epithelium
45Binuclear Giant Cells
- 20 of fetal placenta
- Invade endometrium
- Source
- Placental lactogen
- Pregnancy specific protein B
46Placental 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
47Pregnancy 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!!!
48Diffuse Placenta
Horse
Pig
Microcotyledons
49Microcotelydons
Increase placental surface area
Microcotelydon(Fetal)
Microcotelydon
Epithelium
Microcotelydon (Maternal)
Endometrial Glands
Endometrium
Uterine Arteries
Uterine Veins
50Endometrial 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
51Zonary Placenta(bitch, queen)
52Discoid Placenta(human)
53Cell Layers Separating Maternal and Fetal Blood
Maternal
Fetal
Capillary
Capillary
Endothelium
Endothelium
Connective Tissue
Connective Tissue
Chorionic Epithelium
Endometrial Epithelium
54Histological 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
55Important!!!!
- In all cases, fetal and maternal blood does not
mix.