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Lecture 19 Placentation and Maternal Recognition of Pregnancy

Lecture 19 Placentation and Maternal Recognition of Pregnancy. Animal Science 434 John J. Parrish. Na +. [Na + ]. H 2 O. Blastulation. Gap Junctions. Inner Cell Mass. Zona Pellucida. Trophectoderm. Tight Junctions. Hatching. Bovine 9 - 11 days Equine, Ovine 7 - 8 days Porcine

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Lecture 19 Placentation and Maternal Recognition of Pregnancy

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  1. Lecture 19Placentation and Maternal Recognition of Pregnancy Animal Science 434 John J. Parrish

  2. Na+ [Na+] H2O Blastulation Gap Junctions Inner Cell Mass Zona Pellucida Trophectoderm Tight Junctions

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

  4. Conceptus 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

  5. Development of Porcine Conceptuses from Day 10 to 12 5 mm Spherical 10 mm Spherical Inner Cell Mass 15 mm Tubular 150 mm Filamentous

  6. Elongated Day 15 Porcine Conceptus Embryo

  7. Uterine Location of Elongating Ruminant Blastocyst Corpus Luteum Bovine and Ovine

  8. Pig Intrauterine Migration Day 5

  9. Pig Intrauterine Migration Day 7

  10. Day 12 Embryos become fixed Pig Intrauterine Migration Transuterine migration is rare in cow and ewe!

  11. Trans-uterine Migration in the Mare Begins Day 10 Fixation can occur in either horn! Fixation on day 15 - 16 Corpus Luteum

  12. Gastrulation Trophectoderm Inner Cell Mass Formation of Germ Layers Endoderm Blastocoele Cavity

  13. Endoderm Gastrulation Endoderm Yolk Sack

  14. Endoderm Gastrulation Endoderm Yolk Sack

  15. Gastrula Ectoderm Trophectoderm Endoderm

  16. Gastrula Ectoderm Mesoderm Extraembryonic Coelom Yolk Sack Trophectoderm (Chorion) Endoderm

  17. Ectoderm CNS Sense organs Mammary glands Sweat glands Skin Hair hooves Mesoderm Circulatory Skeletal Muscle Reproductive tracts Kidneys Urinary ducts Germ Layers • Endoderm • Digestive • Liver • Lungs • Pancreas • Thyroid gland • Other glands

  18. Placenta Formation Embryonic Ectoderm Amniotic Folds Extraembryonic Ceolom Yolk Sack Trophectoderm Chorion Mesoderm Endoderm

  19. Amniotic Fold Amniotic Cavity Allantois Extraembryonic Ceolom Yolk Sack Chorion

  20. Amnionic Cavity Amnion Uterine Lumen Allantois Yolk Sack Chorion Extraembryonic Ceolom Carnuncle

  21. Amniotic Cavity Chorion Amnion Allantois Cavity Yolk Sack Allantochorion (Chorioallantois) Cotyledon

  22. 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)

  23. Placental Membranes (cont.) • Allantois • Blood vessels • Fuses with chorion • Allantochorion or chorioallantois • Brings blood vessels to chorion • Chorion • Outermost membrane • Attachment to mother

  24. Maternal Recognition of Pregnancy

  25. Luteal Regression PGF2a (Bovine, Ovine, Porcine) PGF2a (Equine) No Uterine Factor (human)

  26. CL Status CA • Mechanisms • CL Regression • Luteolytic • No CL support • CL Maintenance • Antiluteolytic • Block PGF2aeffects • Luteotrophic • Stimulate progesterone production by CL (+) Uterine PGF2a CL Filamentous Embryo (+) Maintained

  27. Recognition of Pregnancy • Conceptus Secretions • Proteins • Steroids

  28. 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

  29. PGF2a PGF2a Recognition of Pregnancy in the Porcine

  30. E2 E2 E2 PGF2a E2 E2 E2 PGF2a Recognition of Pregnancy in the Porcine PGF2a PGF2a

  31. E2 E2 E2 PGF2a PGF2a E2 PGF2a E2 E2 PGF2a Recognition of Pregnancy in the Porcine • Conceptus Secretions • Estradiol Critical Days 11 to 12 • Mechanism • Antiluteolytic • Redirect PGF2a • Requires 2 embryos per horn

  32. PGF2a PGF2a • Mechanism • antiluteolytic Recognition of Pregnancy in the Mare • Conceptus Secretion • ? Critical Days 10 to 14

  33. HCG Recognition of Pregnancy in the Human • Conceptus Secretes • HCG • Mechanism • luteotrophic • Critical Days • 8 to 12

  34. Recognition of Pregnancy INF-t HCG Estradiol • Conceptus Secretions • Proteins • Steroids

  35. Dog and Cat • CL does not regress if not pregnant • no uterine effect • Psuedopregnancy • CL last similar length as in pregnancy

  36. Implantation

  37. 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

  38. 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

  39. Degree of Tissue Loss at Parturition • Deciduate • Eccentric, interstitial • Rodent, human • Indeciduate or Nondeciduate • Superficial • Farm animals

  40. Shape or Distribution of Chorionic Villi • Cotelydonary - cow, sheep • Diffuse - pig, horse • Zonary - dog, cat • Discoid - human

  41. Concave Cotelydonary Placenta Cow Convex Ewe Cotelydon (Chorion) Caruncle 70 - 120 90 - 100 Endometrium

  42. Cotelydonary Placenta Cow Ewe Placentome

  43. 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

  44. Day 23 Migration of Bicnucleate Cells and Formation of Syncytium Binucleate Cell Endometrial Stroma Multinucleated Cells in Uterine Epithelium

  45. Binuclear Giant Cells • 20% of fetal placenta • Invade endometrium • Source • Placental lactogen • Pregnancy specific protein B

  46. Placental Lactogens (Protein Hormones) Prolactin-like activity: Stimulates Milk Synthesis NotPresent 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

  47. 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!!!

  48. Diffuse Placenta Horse Pig Microcotyledons

  49. Microcotelydons Increase placental surface area Microcotelydon(Fetal) Microcotelydon Epithelium Microcotelydon (Maternal) Endometrial Glands Endometrium Uterine Arteries Uterine Veins

  50. 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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