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Lecture 19 Placentation and Maternal Recognition of Pregnancy

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Lecture 19 Placentation and Maternal Recognition of Pregnancy 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. 10.
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