Pregnancy and Parturition 2024 Ross University PDF

Pregnancy and parturition L. Segabinazzi 2024 Maternal recognition of pregnancy Number Pregnant and non-pregnant cycle similar for first 14ish days Suppression of PGF2α Luteotropic mechanism Mechanism not completely understood in mares this in...

Pregnancy and parturition L. Segabinazzi 2024 Maternal recognition of pregnancy Number Pregnant and non-pregnant cycle similar for first 14ish days Suppression of PGF2α Luteotropic mechanism Mechanism not completely understood in mares this in Fators for specie Embryo mobility - Interferon tau (IFNT) - Estrogens - 2 Chorionic gonadotropin -  Maternal recognition P h y s i o l o g y I IMM - Reproduction of pregnancy Maternal recognition = blocking luteolysis Attachmen/implantation = placentation occurs - the blastocyst hatches as the embryo, adheres, and invades into the wall of the female's uterus.  Placenta P h y s i o l o g y I IMM - Reproduction Temporary organ Formed by extraembryonic membranes Trophoblast (Corion) Extraembryonic mesoderm (Umbilicar cord, allantois) Extraembryonic ectoderm (Amnion) Maternal (endometrium) and fetal components (chorion) Functions of the placenta Protection Nutrition Respiration Excretion Hormone production  Fetal membranes in domestic animals P h y s i o l o g y I IMM - Reproduction Yolk sac – nutrition and sex differentiation Yolk-sac placenta – yolk sac fuses with the chorion rather than the alantois Amnion – amniotic fluid is important for mechanic protection, hydration, temperature changes, fetus movement – mostly water from other cells Umbilical cord – one vein, two arteries, urachus – nutrition of the embryo and secretion (extraembryonic mesoderm origin) Allantois - collect secretions from the embryo and helps with gases exchanges Chorion (outermost fetal membrane) – external layer of the placenta that attaches with the uterus - nutrition of the embryo  Placenta P h y s i o l o g y I IMM - Reproduction Placental development Pre-implantation Embryonic cells differentiate in ICM and trophoblast Implantation Blastocyst hatches (loses the ZP) Trophoblast cells invade the endometrium Post-implantation Establishment of circulation End of pregnancy Reduce exchange between the maternal and fetal circulations - parturition Placental delivery  Implantation P h y s i o l o g y I IMM - Reproduction Placenta Structurally, placenta has two different parts lying in close proximity : 1. Fetal component - Chorion i. Fetal blood capillaries ii. Fetal connective tissue iii. Fetal chorionic epithelium each other II face 2. Maternal component – Uterine endometrium i. Uterine epithelium (mucosa) ii. Uterine connective tissue iii. Maternal blood capillaries Feto-maternal exchanges depend on the degree of connection between the fetal component and the maternal componente.  Classification of placentation P h y s i o l o g y I IMM - Reproduction Source of Vascular supply – “development of the umbilical cord” Degree of Involvement of Foetal and Maternal Tissues – number of tissue layer in the maternal and fetal component Nature of contact/intimacy of attachment – uterine bleeding after parturition Distribution of villi/attachment to the endometrium  Source of Vascular supply P h y s i o l o g y I IMM - Reproduction From the Vitelline circulation of the yolk sac or Allantoic circulation provided by the allantois: 1. Chorio-vitelline/ Yolk-sac placenta – Highly vascular yolk sac fuses with the chorion E.g., Metatherian mammals – Marsupials , Didelphis and Macropus 2. Chorio-allantoic placenta- Allantois with its blood vessels fuses with the chorion – yolk sac disappears E.g., Some Marsupials and all Eutherian mammals  Degree of Involvement of Foetal and P h y s i o l o g y I IMM - Reproduction Maternal Tissues Epithelio-chorial – The trophoblast or chorionic epithelium and uterine epithelium remain in close contact, but there is no invasion by the trophoblast cells – no transfer of antibodies and immune cells to the fetus 6 layers tetisse E.g., Marsupials, pig, horses, camelids of Syndesmo-chorial – Chorionic villi erode the uterine wall, so that the uterine epithelium is ruptured and the chorionic villi comes in contact with the connective tissue of the uterine wall - no transfer of antibodies and immune cells to the fetus E.g., Sheep & Cow (ruminants) Only one connection to mom the plactors Endothelio-chorial – Both uterine epithelium and connective tissue are eroded so that the chorionic villi comes in contact with the endothelium of maternal blood vessel - only 5–10% of maternal antibodies are transferred via trans-placenta to the fetus. and convtin tissue E.g., Dogs ,Cats & other carnivores loose the material epithelium Haemo-chorial – Uterine epithelium, connective tissue, and endothelium all are eroded, and the chorionic villi baths in the maternal blood – IgG is transferred via transplacental to the fetus to 3 layers in the fetus e.g., Human, mouse, guinea pig There is just Haemo-endothelial – Foetal capillaries lie freely in maternal blood – antibodies, mostly IgG, are transferred. and connective tissue E.g., Rabbit Fetus loose the epithelium 3  Mom y of do not have Degree of Involvement of Foetal and P h y s i o l o g y I IMM - Reproduction Maternal Tissues Epitheliochorial Intact membranes both sides Horse, pig, Syndesmochorial (Type of Ephiteliochorial placenta) Fetal-maternal syncytium Ruminants Endotheliochorial Dog and cat Hemochorial Human, mouse, guinea pig put  Intimacy of attachment P h y s i o l o g y I IMM - Reproduction Non-deciduate (adeciduate) placenta – Implantation superficial; fetal chorionic epithelium lies in contact with the uterine epithelium and at the time of birth the fetal villi are drawn out completely without tearing or causing injury to the uterine wall and no bleeding occurs E.g., Pigs, Cattles, Horse & other Ruminats Deciduate (Deciduos) placenta – Implantation is more intimate; the wall of the uterus become eroded so that the fetal chorionic epithelium may come to lie either in the connective tissue or into the maternal blood and at the time of parturation when fetal part separate from the uterine part of the placenta there is more or less extensive bleeding or haemorrhage and tearing of tissue from the uterine wall bleed there is a non They E.g., Man, Rabbit, Dog, Cat, of degrade of layers Contra-Deciduate placenta – implantation or association is intimate but both fetal and maternal tissue are absorbed “in situ” by maternal leucocytes – PLACENTA IS NOT DELIVERED E.g., Parameles and Talpa (mole)  Distribution of villi/attachment to the endometrium P h y s i o l o g y I IMM - Reproduction Diffused – Villi scattered all over the surface of chorion e.g., Mare, Lemur, Pig Cotyledonary – Villi distributed in isolated patches e.g., Ruminants like Deer, Sheep, Cattle Zonary – Villi arranged in definite band or girdle encircling the middle of blastocyst or chorion sac e.g., Carnivores (Cats, Dogs), elephants Discoidal – Villi located in one or two discoidal areas or patches e.g., Mouse, Rat, Rabbit, Monkey, Apes and Man  Shape P h y s i o l o g y I IMM - Reproduction Diffuse Zonary Discoid Horse, pig, camelid Carnivors (Dog, Human, mouse cat), elephants Cotyledonary Cow, sheep, goat  Characterization of the placenta P h y s i o l o g y I IMM - Reproduction 1. Distribution of villi/attachment to the endometrium 2. Source of Vascular supply will be always chorioallatoic everyone 3. Degree of Involvement of Foetal and Maternal Tissues 4. Nature of contact/intimacy of attachment Ruminants: cotyledonary, chorioallantoic, epitheliochorial, and syndesmochorial, adeciduate (qualified) Equine and camelids: diffuse, chorioallantoic, epitheliochorial, villous (microcotyledonary), adeciduate Pigs: diffuse, chorioallantoic, epitheliochorial, adeciduate – present “necrotic tips” Canine and feline: zonary, chorioallantoic, endotheliochorial, deciduate  Endocrinology of the placenta P h y s i o l o g y I IMM - Reproduction Progesterone – essential for pregnancy Estrogens (fetalplacental unit) - triggers the development of the placenta and baby's organs Relaxin – helps the body prepare for delivery by loosening the muscles and ligaments in the pelvis. Placental lactogen – regulates the metabolism, and is a major regulator of glucose, amino acid, and lipid metabolism in the mother, aiding in the mobilization of nutrients for transport to the fetus Chorionic gonadotrophin (Primates) – luteotropic hormone responsible for maternal recognition of pregnancy Prolactin - stimulate breast tissue development and milk production Equine Chorionic gonadotrophin (equines) - produced by endometrial cups – responsible for the formation of secondary/accessory corpus luteum  Progesterone in pregnancy P h y s i o l o g y I IMM - Reproduction Maintenance of Pregnancy Species Source Progesterone (or progestogen) is an absolute Sheep Placenta requirement for mammalian pregnancy Goat CL Placental development and function Cow CL Myometrial quiescence Mare Fetoplac.U Cervical closure Dog CL Immune mediation (mitigate immune Cat CL response) Pig CL Rat/Mouse CL Primate Fetoplac.U Guinea Pig Placenta Cattle M MM are Fetal-placental progestin Bovine placenta produces progesterone (P4); however, the corpus luteum is the major source of P4 responsible for maintaining pregnancy. Cow’s placenta produces a bunch of estrogens (estrone-3-sulfate) Dogs M MM are Fetal-placental progestin The only hormone required to maintain pregnancy in dogs is progesterone, based on pregnancies so maintained in ovariectomized bitches supplemented with progesterone. The only source of progesterone in dogs is ovarian (corpora luteal). luteum Corpus Normal estrogen concentrations may however be important for full mammary development and lactation. Horses M MM are Fetal-placental progestin te same the Ch was Before source aftery Primarily 5α-pregnanes Similar to P4 Bind to P4 receptors First appear around Day 40 Increase gradually until Day 300  Endometrial cups (Only in equids) Allantoic pouches Migration of chorionic girdle cells into maternal endometrium Approx. Day 35 End. cups Produce equine chorionic gonadotropin (eCG) similar to FSH Yolk sac Detectable about Day 35 and LH Peaks about Day 60 Chorionic girdle Disappears Day 100 – 150 eCG similar to LH and FSH Allantois Horses M MM are eCG Like-Lh and –FSH molecule Induce formation of accessory CL Secondary/accessory corpora lutea augment progesterone production by primary CL All CLs (primary and secondary) degenerate by about Day 150 of pregnancy Mom’s immune response (foreign body) Subsequent progestin production is by placenta  Fetal-placental estrogens Partnership between fetal gonads and placenta Fetal gonads produce androgens Androgens aromatized to estrogens in placenta Estrogens used to evaluate fetal wellbeing Relaxin M MM are Important for parturition Source mares vs. cows Produced by CL and placenta in mares Produced only by the CL in cows No problem in ovariectomized mares vs. Cows (dystocia)  Gestation Length P h y s i o l o g y I IMM - Reproduction Species Duration (d) Notes Cow 283 Longer in B.indicus 9m Doe 148-155 Breed differences Sm Ewe 145-155 Breed differences SM Mare 330-340-350-360 Season; variable 11M Sow 114 (3m3w3d) 3M3W3d Bitch 65 From LH peak Queen 63-68 From ovulation  Physiology of Parturition P h y s i o l o g y I IMM - Reproduction The control of timing of labour is complex involving relans interactions between mother, fetus and the placenta. hypotulums The onset of the cascade compromises the activation of cortisol Fetal hypothalamic-pituitary-adrenal axis Associated with the increased expression of oxytocin and PGF 0 receptors contention Fetal hypoxemia in late pregnancy Placental adequacy, fetal size Corticotropin-releasing (CRH) → Adrenocorticotropic hormone (ACTH) → Cortisol Fetal maturation High cortisol levels Final maturation of fetal lung, kidneys, brain Switch in P4:E2 ratio Increased production of prostaglandins/oxytocins by placenta and uterus Relaxin and estrogens play roles in softening of ligaments and Cervical ripening  Phases of parturition P h y s i o l o g y I IMM - Reproduction Stage 1 Stage 2 Stage 3 Proper labor – expulsion of Relaxation of the pelvic Fetal membranes the fetus ligaments, and dilation of delivery the cervix, vagina, and vulva. Fergusson’s Reflex – pressure on the cervix by the fetus (end of stage 1)  Antena Transition from intrauterine to P h y s i o l o g y I IMM - Reproduction Extrauterine Life Neonate The transition from a fetus to a newborn is the most complex adaptation Respiration charges - Lung adaptation requires the coordinated clearance of fetal lung fluid, surfactant secretion, and the onset of consistent breathing. Circulatory changes - With the removal of the low-pressure placenta, the cardiovascular response requires striking changes in blood flow, Primary mediators of fetal pressures and pulmonary vasodilation. maturation - cortisol Thermoregulation and control the energy metabolism  Lorenzo Segabinazzi, DVM, MSc, PhD Ross University School of Veterinary Medicine THANK YOU [email protected] VETERINARY.ROSSU.EDU ©2021 Ross University School of Veterinary Medicine. All rights reserved.