Lecture 19 Placentation and Maternal Recognition of Pregnancy

Lecture 19 Placentation and Maternal Recognition of Pregnancy

Placentation and Maternal Recognition of Pregnancy Animal Science 434 John J. Parrish Blastulation Gap Junctions Inner Cell Mass Na +

Zona Pellucida [Na ] + Trophectoderm H2O Tight Junctions Hatching Bovine 9 - 11 days

Equine, Ovine 7 - 8 days Porcine 6 days Conceptus Growth Occurs in cow, pig and sheep Spherical Tubular

Filamentous Cow Day 15, 1-2 mm Day 18-19, 10-20 cm Embryonic Area Elongating Trophoblast Mare remains spherical!

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

Conceptus Embryo Uterine Location of Elongating Ruminant Blastocyst Bovine and Ovine Corpus Luteum Pig Intrauterine Migration

Day 5 Pig Intrauterine Migration Day 7 Pig Intrauterine Migration Day 12 Embryos become fixed

Transuterine migration is rare in cow and ewe! Trans-uterine Migration in the Mare Begins Day 10 Fixation can occur in either horn! Fixation on day 15 - 16

Corpus Luteum Gastrulation Trophectoderm Inner Cell Mass Formation of Germ Layers Endoderm

Blastocoele Cavity Gastrulation Endoderm Yolk Sack Gastrulation Endoderm Yolk Sack

Gastrula Ectoderm Trophectoderm Endoderm Gastrula Ectoderm Extraembryonic Coelom Mesoderm

Yolk Sack Endoderm Trophectoderm (Chorion) 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 Embryonic Ectoderm

Placenta Formation Amniotic Folds Extraembryonic Ceolom Yolk Sack Trophectoderm Mesoderm Chorion Endoderm

Amniotic Fold Amniotic Cavity Allantois Yolk Sack Extraembryonic Ceolom Chorion

Amnionic Cavity Yolk Sack Amnion Uterine Lumen Allantois Chorion

Extraembryonic Ceolom Carnuncle Chorion Amniotic Cavity Amnion Allantois Cavity Yolk Sack Allantochorion

(Chorioallantois) Cotyledon 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) Placental Membranes (cont.) Allantois Blood vessels Fuses with chorion Allantochorion or chorioallantois Brings blood vessels to chorion Chorion

Outermost membrane Attachment to mother Maternal Recognition of Pregnancy Luteal Regression PGF2 (Bovine, Ovine, Porcine) PGF2 (Equine) No Uterine Factor

(human) CL Status CA CL (+) Uterine PGF2 Filamentous Embryo (+) Maintained

Mechanisms CL Regression Luteolytic No CL support CL Maintenance Antiluteolytic Block PGF2effects Luteotrophic Stimulate progesterone production by CL Recognition of Pregnancy

Conceptus Secretions Proteins Steroids Recognition of Pregnancy in Bovine and Ovine Mechanism Antiluteolytic Inhibit oxytocin receptor synthesis Inhibit PGF2 synthesis

Conceptus Secretions Interferons oIFN- bIFN- Critical Days Bovine - 16 to 17 Ovine - 12 to 13 Recognition of Pregnancy in the Porcine PGF2 PGF2

Recognition of Pregnancy in the Porcine E2 E2 E2 PGF2 2 PGF2 2

E2 E2 E2 PGF2 PGF2 Recognition of Pregnancy in the Porcine Conceptus Secretions Estradiol

E22 E22 E22 PGF2 2 Critical Days PGF2 2 11 to 12

E22 PGF2 E22 E22 PGF2 Mechanism Antiluteolytic Redirect PGF2 Requires 2 embryos per horn

Recognition of Pregnancy in the Mare PGF2 Conceptus Secretion ? Critical Days 10 to 14 PGF2 Mechanism antiluteolytic Recognition of Pregnancy in the Human

Conceptus Secretes HCG Mechanism luteotrophic HCG Critical Days 8 to 12 Recognition of Pregnancy Conceptus Secretions Proteins Steroids

INF- HCG Estradiol Dog and Cat CL does not regress if not pregnant no uterine effect Psuedopregnancy CL last similar length as in pregnancy Implantation

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 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 Degree of Tissue Loss at Parturition Deciduate

Eccentric, interstitial Rodent, human Indeciduate or Nondeciduate Superficial Farm animals Shape or Distribution of Chorionic Villi Cotelydonary - cow, sheep Diffuse - pig, horse Zonary - dog, cat Discoid - human Cotelydonary

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

Cotelydonary Placenta Cow Placentome Ewe Placental Attachment in Ruminant Binucleate Cell

Chorion Migrate and fuse with uterine epithelium Uterine Epithelium Syncytium Capillary Stroma

Fusion of Binucleate cells and uterine epithelium (multinucleate) Day 23 Migration of Bicnucleate Cells and Formation of Syncytium Binucleate Cell

Endometrial Stroma Multinucleated Cells in Uterine Epithelium Binuclear Giant Cells 20% of fetal placenta Invade endometrium Source Placental lactogen Pregnancy specific protein B

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 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!!! Diffuse Placenta Horse Pig Microcotyledons

Microcotelydons Microcotelydon (Fetal) Increase placental surface area Microcotelydon Epithelium Endometrial Glands Uterine

Arteries Endometrium Microcotelydon (Maternal) Uterine Veins 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 Zonary Placenta (bitch, queen) Discoid Placenta (human) Cell Layers Separating Maternal and Fetal Blood Fetal Maternal

Capillary Capillary Endothelium Endothelium Connective Tissue Chorionic Epithelium

Connective Tissue Endometrial Epithelium Histological Classification Tissues syndesmochorial endothelialchorial hemochorial

hemoendothelial Maternal endothelium + conn. tissue + epithelium + + + - + -

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

+ + + + + + + *ruminant dog

cat human rat rabbit Species epithelialchorial pig horse ruminant

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

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