Blastulation Gap Junctions Lecture 19 Inner Cell Mass Zona Pellucida Placentation and Maternal Recognition of Pregnancy Trophectoderm Na+ [Na+] Animal Science 434

John J. Parrish H2O

Tight Junctions

Hatching Conceptus Growth Cow • Day 15, 1-2 mm Occurs in cow, pig and sheep  Bovine • Day 18-19, 10-20 cm »9 - 11 days Spherical Embryonic  Equine, Ovine Area »7 - 8 days  Porcine Tubular Elongating »6 days Trophoblast

Filamentous Mare remains spherical!

Development of Porcine Conceptuses Elongated Day 15 Porcine from Day 10 to 12 Conceptus

5 mm Spherical 10 mm Spherical

Inner Cell Mass 15 mm Tubular

150 mm Filamentous Embryo

1 Uterine Location of Elongating Pig Intrauterine Migration Ruminant Blastocyst

Day 5

Corpus Luteum Bovine and Ovine

Pig Intrauterine Migration Pig Intrauterine Migration

Day 7 Day 12

Embryos become fixed Transuterine migration is rare in cow and ewe!

Trans-uterine Migration in the Mare Gastrulation Begins Day 10 Inner Cell Mass Trophectoderm

Formation Endoderm of Germ Fixation can Fixation occur in either on day Layers horn! 15 - 16 Blastocoele Corpus Cavity Luteum

2 Gastrulation Gastrulation

Endoderrm Endoderrm

Yolk Sack Yolk Sack

Gastrula Gastrula

Ectoderm Ectoderm Mesoderm Ectoderm Trophectoderm Trophectoderm Extraembryonic Coelom

Yolk Sack

Endoderm

Endoderm Trophectoderm (Chorion)

Germ Layers Placenta Formation Embryonic Amniotic Folds  Ectoderm  Mesoderm  Endoderm Ectoderm » CNS » Circulatory » Digestive » Sense organs » Skeletal » Liver » Mammary » Muscle » Lungs glands » Reproductive » Pancreas Extraembryonic » Sweat glands tracts » Thyroid gland Ceolom » Skin » Kidneys » Other glands Yolk » Hair » Urinary ducts Sack » hooves

Trophectoderm Chorion Mesoderm Endoderm

3 Amniotic Fold Amnionic Cavity Amniotic Cavity Amnion Uterine Lumen

Allantois

Extraembryonic Yolk Ceolom Allantois Sack Yolk Sack Chorion

Chorion Extraembryonic Carnuncle Ceolom

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

Allantochorion Cotyledon (Chorioallantois)

Placental Membranes (cont.)

 Allantois »Blood vessels »Fuses with chorion • Allantochorion or chorioallantois Maternal Recognition of Pregnancy • Brings blood vessels to chorion  Chorion »Outermost membrane »Attachment to mother

4 Luteal Regression CL Status

CA Mechanisms

CL Regression •Luteolytic (+) •No CL support

CL Uterine PGF2α CL Maintenance PGF •Antiluteolytic 2α » Block PGF effects (Bovine, Ovine, Filamentous Embryo 2α PGF •Luteotrophic Porcine) 2α (+) (Equine) » Stimulate progesterone production by CL No Uterine Factor Maintained (human)

Recognition of Pregnancy in Bovine Recognition of Pregnancy and Ovine

Conceptus Secretions • Interferons Mechanism •oIFN-τ Conceptus Secretions • Antiluteolytic •bIFN-τ • Proteins • Inhibit oxytocin • Steroids receptor synthesis Critical Days • Inhibit PGF2α synthesis • Bovine - 16 to 17 • Ovine - 12 to 13

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

E 2 E2

PGF2α E2

PGF2α PGF2α PGF2α E E2 2

E2

PGF2α PGF2α

5 Recognition of Pregnancy in the Porcine Recognition of Pregnancy in the Mare Conceptus Secretions • Estradiol E2 E2

Critical Days PGF2α

E2 PGF2α 11 to 12 PGF2α E2

E2

E2 PGF2 α PGF2α

PGF2α Mechanism Conceptus Secretion Mechanism •Antiluteolytic • ? • antiluteolytic »Redirect PGF2α Critical Days »Requires 2 embryos per horn 10 to 14

Recognition of Pregnancy in the Human Recognition of Pregnancy

Conceptus Secretes • HCG

Mechanism • luteotrophic INF-τ HCG HCG Conceptus Secretions Critical Days Estradiol •8 to 12 • Proteins • Steroids

Dog and Cat

 CL does not regress if not pregnant »no uterine effect  Psuedopregnancy »CL last similar length as in pregnancy Implantation

6 Time of Implantation Type of Implantation

Attachment to Uterus  Superficial Species Beginning Completion »Chorion lies opposed to uterine wall »Farm animals pig 13 24  Eccentric cow 22 40 »Chorionic sack in a uterine fold sheep 15 28 »Rodent mare 24 - 40 95 - 100  Interstitial human 7 - 8 30 »Embryo digests part of uterine wall »human

Degree of Tissue Loss at Parturition Shape or Distribution of Chorionic Villi

 Deciduate  Cotelydonary - cow, sheep »Eccentric, interstitial  Diffuse - pig, horse »Rodent, human  Zonary - dog, cat  Indeciduate or Nondeciduate  Discoid - human »Superficial »Farm animals

Cotelydonary Cotelydonary Placenta Placenta

Cow Cow

Convex Ewe Placentome Ewe Cotelydon (Chorion) Concave

Caruncle

70 - 120 90 - 100 Endometrium

7 Placental Attachment in Ruminant Day 23 Migration of Bicnucleate Cells and Formation of Syncytium

Binucleate Chorion Cell

Migrate and fuse with uterine Binucleate Uterine epithelium Cell Epithelium

Syncytium Capillary Fusion of Binucleate Endometrial cells and Stroma uterine Stroma epithelium Multinucleated Cells in (multinucleate) Uterine Epithelium

Binuclear Giant Cells Placental Lactogens (Protein Hormones)

 20% of fetal placenta Prolactin-like activity: Stimulates Milk Synthesis  Invade endometrium Not Present in Pig and Mare  Source »Placental lactogen • May regulate maternal metabolism to facilitate fetal growth »Pregnancy specific protein B • High levels in the last 1/3 of gestation.

• High levels facilitate higher milk production.

• Dairy cows have higher blood concentrations than beef cows

Pregnancy Specific Protein B Diffuse Placenta Horse  Unique to ruminants Pig  Function uncertain  Has been used to detect pregnancy »Cattle, sheep, deer • Can be used to detect pregnancy in cows after day 25 »Not earlly pregnancy factor!!!

Microcotyledons

8 Microcotelydons Increase placental Endometrial Cups in Mare surface area Microcotelydon  From both trophoblast and endometrium (Fetal) (Fetal) Microcotelydon  5 to 10 Epithelium  Form between days 35 to 60

Microcotelydon E  Produce equine chorionic gonadotropin

(Maternal) n d (eCG, PMSG) o m

Endometrial e  Sloughed off after day 60 t

Glands r i u m

Uterine Arteries Uterine Veins

Zonary Placenta Discoid Placenta (bitch, queen) (human)

Cell Layers Separating Maternal and Fetal Blood Histological Classification Fetal Maternal

Tissues epithelial- syndesmo- endothelial- hemo- hemo- Capillary Capillary chorial chorial chorial chorial endothelial Maternal endothelium + + + - - conn. tissue + + - - - epithelium + - - - -

Fetal epithelium + + + + - Endothelium Endothelium conn. tissue + + + + - endothelium + + + + +

Connective Connective Species pig *ruminant dog human rat Tissue Tissue horse cat rabbit Chorionic Endometrial ruminant Epithelium Epithelium

9 Important!!!!

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

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