PLACENTA & MEMBRANES.pptx

an overview of placenta and membranes. Whether you're a medical professional, researcher, student, or simply intrigued by the wonders of human biology, this presentation promises to provide valuable insights into the marvels of the placenta and membranes.

1. PLACENTA & MEMBRANES MODERATOR: Dr. Sana Ansari PRESENTER: Dr. Rahul Shah PGY1 Department of Obstetrics & Gynaecology 11/4/2023

2. OUTLINES PLACENTA & its DEVELOPMENT STRUCTURES FUNCTIONS PLACENTAL PATHOLOGY FUNCTIONS FETAL MEMBRANES AMNIOTIC FLUID 11/4/2023

3. PLACENTA Discoid Hemochorial Deciduate 11/4/2023

4. DEVELOPMENT Formed by 2 sources. FETAL SOURCES: Chorion Frondosom MATERNAL SOURCES: Decidua Basalis 11/4/2023

5. 11/4/2023 DAY 11: Intersitial implantation completed DAY 13: stem villi developed from trabeculae which connect chorionic plate with basal plate Primary, secondary and tertiary villi formed from stem villi DAY 21: Arterial-capillary-venous system in mesenchymal core of each villi completed

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8. PLACENTA AT TERM Diameter: 15-20 cm Thickness: 3 cm at the center Weight: 500gms (1:6) Occupies 30% of uterine wall TWO SURFACES: Fetal and Maternal and a peripheral margin 11/4/2023

9. FETAL SURFACE Chorionic plate Covered by smooth and glistening amnion with umbilical cord attached at or near center Branches of umbilical vessels are visible beneath the amnion as they radiate from the insertion of cord. Amnion can be peeled off from the chorion except for the center 4/5 of placenta is of fetal origin 11/4/2023

10. MATERNAL SURFACE Basal Plate is rough and spongy Dull red color Remnant of decidua basalis may be visible ( thin grayish and shaggy) Lobes or cotyledons 15-20 Numerous grayish spots: deposition of calcium Less than 1/5 th Only the decidua basalis and the blood in intervillous space are of maternal origin 11/4/2023

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12. MARGIN Peripheral Margin: limited by fused basal and chorionic plate Continuous with chorion laeve and amnion Attachment Due to anchoring villi connecting chorionic plate with basal plate and also by fused decidua capsularis and vera with the chorion leave at the margin Usually upper body of uterus encroaching fundus (anterior or posterior wall) Separation After birth of baby Line of separation is through the decidua spongiosum 11/4/2023

13. STRUCTURES AMNIOTIC MEMBRANE: single layer, cubicle epithelium loosely attached to the adjacent chorionic plate. CHORIONIC PLATE: From within outward it consists of Primitive mesenchymal tissue containing branches of umbilical vessels, layer of cytotrophoblast and syncyttiotrophoblast . The stem villi arise from this plate. BASAL PLATE: Part of spongy layer of decidua basalis, Nitabuch layer of fibrinoid degeneration of outer syncytiotrophoblast at the junction of cytotrophoblast, cytotrophoblastic shell and syncytiotrophoblast 11/4/2023

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16. 11/4/2023 STEM VILLI

17. STRUCTURE OF A TERMINAL VILLUS In the early placenta , each terminal villus has got the following structures from outside inward: (1) Outer syncytiotrophoblast (2) Cytotrophoblast (3) Basement membrane (4) Central stroma containing fetal capillaries, primitive mesenchymal cells, connective tissue and a few phagocytic (Hoffbauer) cells 11/4/2023

18. PLACENTAL CIRCULATION 11/4/2023 UTEROPLACENTAL CIRCULATION FETOPLACENTAL CIRCULATION Between Mother and Placenta Fetus and placenta Present in Intervillious Space Villi Formed by Day 15 Day 17 Via Spiral Arteries Umbilical Artery No. of spiral arteries that open in internal space: 120-200 O2 saturation of interval space: 65-75% Partial pressure in interval space: 30-35% Uteroplacental blood flow at term: 500-750ml/min Uterine blood flow at term: 750ml/min Fetoplacental Blood flow at term: 400ml/min Fetal blood flow at term: 125ml/kg Rate of O2 delivery to fetus: 8ml/kg/min

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20. PLACENTAL BARRIER (PLACENTAL MEMBRANE) 11/4/2023

21. PLACENTAL AGING 11/4/2023

22. DECIDUAL CHANGES There is an area of fibrinoid degeneration where trophoblast cells (covered with syncytium) meet the decidua. This zone is known as Nitabuch layer . This layer limits further invasion of the decidua by the trophoblast. The membrane is absent in placenta accreta . 11/4/2023

23. INTERVILLOUS SPACE The syncytium covering the villi and extending into the decidua of intervillous space undergoes fibrinoid degeneration and form a mass entangling variable number of villi. These are called white infarcts which vary in size from few millimetres to a centimetre or more. Calcification or even cyst formation may occur on it. Such type of degeneration is usually near the placental margin. There may be inconsistent deposition of fibrin called Rohr ’ s stria at the bottom of the intervillous space and surrounding the fastening villi. 11/4/2023

24. PLACENTAL FUNCTIONS 1. Transfer of nutrients and waste products between the mother and fetus. In this respect it attributes to the following functions: • Respiratory • Excretory • Nutritive 2. Endocrine function: Placenta is an endocrine gland. It produces both steroid and peptide hormones to maintain pregnancy 3. Barrier function. 4. Immunological function. 11/4/2023

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26. MECHANISM INVOLVED IN PLACENTAL TRANSFER Bulk flow and solvent drag Simple diffusion. Facilitated diffusion . Active transfer Endocytosis Exocytosis Leakage 11/4/2023

27. Respiratory function: fetal respiratory movements are observed as early as 11 weeks, there is no gaseous exchange. Intake of oxygen and output of carbon dioxide take place by simple diffusion across the fetal membrane. The oxygen supply to the fetus is at the rate of 8 mL/Kg/min and this is achieved with cord blood flow of 165–330 mL/min . 11/4/2023

28. Excretory function Waste products from the fetus such as urea, uric acid, and creatinine are excreted to the maternal blood by simple diffusion 11/4/2023

29. Nutritive function: Glucose: Facilated Diffusion Via GLUT I Lipids Amino Acids: Active Transport Water and Electrolytes: Simple diffusion and Active Transport Hormones 11/4/2023

30. BARRIER FUNCTION Fetal membrane has long been considered as a protective barrier to the fetus against noxious agents circulating in the maternal blood. substances of high molecular weight of more than 500 daltons are held up but there are exceptions. Antibody and antigens in immunological quantities can traverse across the placental barrier in both directions. The transfer of the larger molecule is probably facilitated by pinocytosis. Maternal infection during pregnancy by virus (rubella, chickenpox, measles, mumps, poliomyelitis), bacteria ( Treponema pallidum, Tubercle bacillus ) or protozoa ( Toxoplasma gondii , malaria parasites) may be transmitted to the fetus across the so called placental barrier and affect the fetus in utero. 11/4/2023

31. IMMUNOLOGICAL FUNCTION The fetus & placenta contains paternally determined antigens: but no graft rejection SP1, EPF, PAPP-A, Steroid & chronic gonadotropin have got some immunosuppressive effect. Shift of maternal response from cell mediated to humoral (TH1 to TH2) Decidual NK cells and trophoblast HLA class 1 molecule interact. The cytokine thus derived regulates the invasion of extravillious trophoblastic cells into spiral arteries converted to low resistance and high conductance. 11/4/2023

32. PLACENTAL ABNORMALITIES 11/4/2023

33. DEFINITION 11/4/2023

34. BILOBED PLACENTA 11/4/2023

35. SUCCENTURIATE PLACENTA 11/4/2023

36. FENESTRATE PLACENTA 11/4/2023

37. CIRCUMVELLET PLACENTA 11/4/2023

38. MEMBRANOUS PLACENTA 11/4/2023

39. BATTLEDORE PLACENTA 11/4/2023

40. FETAL MEMBRANES 2 LAYERS: OUTER CHORION & INNER CHORION 11/4/2023

41. CHORION It represents the remnant of chorion laeve and ends at the margin of the placenta. Thicker than amnion, friable and shaggy on both the sides. Internally, it is attached to the amnion by loose areolar tissue and remnant of primitive mesenchyme. Externally, it is covered by vestiges of trophoblastic layer and the decidual cells of the fused decidua capsularis and parietalis which can be distinguished microscopically Therefore human placenta is a discoid , deciduate , larynthine and haemochorial type 11/4/2023

42. AMNION It is the inner layer of the fetal membranes. Its internal surface is smooth and shiny and is in contact with liquor amnii . The outer surface consists of a layer of connective tissue and is apposed to the similar tissue on the inner aspect of the chorion from which it can be peeled off. The amnion can also be peeled off from the fetal surface of the placenta except at the insertion of the umbilical cord 11/4/2023

43. Functions : Contribute to the formation of liquor amnii Intact membranes prevent ascending uterine infection Facilitate dilatation of the cervix during labor Has got enzymatic activities for steroid hormonal metabolism Rich source of glycerophospholipids containing arachidonic acid — precursor of prostaglandin E2 and F2 a . 11/4/2023

44. AMNIOTIC CAVITY, AMNION AND AMNIOTIC FLUID 11/4/2023

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46. AMNIOTIC FLUID ORIGIN OF AMNIOTIC FLUID: not well understood. It is probably of mixed maternal and fetal origin. CIRCULATION: completely changed and replaced in every 3 hours as shown by the clearance of radioactive sodium injected directly into the amniotic cavity. The presence of lanugo and epithelial scales in the meconium shows that the fluid is swallowed by the fetus and some of it passes from the gut into the fetal plasma VOLUME: Amniotic fluid, volume is related to gestational age. It measures about 50 mL at 12 weeks, 400 mL at 20 weeks and reaches its peak of 1 liter at 36–38 weeks. Thereafter the amount diminishes, till at term it measures about 600–800 mL . As the pregnancy continues post term, further reduction occurs to the extent of about 200 mL at 43 weeks. 11/4/2023

47. PHYSICAL FEATURES: The fluid is faintly alkaline with low specific gravity of 1.010. It becomes highly hypotonic to maternal serum at term pregnancy. An osmolarity of 250 mOsmol /L is suggestive of fetal maturity . The amniotic fluid’s osmolality falls with advancing gestation. Color: In early pregnancy, it is colorless but near term it becomes pale straw colored due to the presence of exfoliated lanugo and epidermal cells from the fetal skin. It may look turbid due to the presence of vernix caseosa. 11/4/2023

48. Abnormal color Deviation of the normal color of the liquor has got clinical significance. — Meconium stained (green) is suggestive of fetal distress in presentations other than the breech or transverse. Depending upon the degree and duration of the distress, it may be thin or thick or pea souped (thick with flakes). Thick with presence of flakes suggests chronic fetal distress. — Golden color in Rh incompatibility is due to excessive hemolysis of the fetal RBC and production of excess bilirubin. — Greenish yellow (saffron) in post maturity. — Dark colored in concealed accidental hemorrhage is due to contamination of blood. — Dark brown (tobacco juice) amniotic fluid is found in IUD. The dark color is due to frequent presence of old HbA . 11/4/2023

49. COMPOSITION In the first half of pregnancy, the composition of the fluid is almost identical to a transudate of plasma. But in late pregnancy, the composition is very much altered mainly due to contamination of fetal urinary metabolites. The composition includes—(1) water 98–99% and (2) solid (1–2%). The following are the solid constituents : (a) Organic: Protein–0.3 mg% NPN–30 mg% Total lipids–50 mg% Glucose–20 mg% Uric acid–4 mg% Hormones (Prolactin, insulin and renin) Urea–30 mg% Creatinine–2 mg% 11/4/2023

50. CLINICAL IMPORTANCE: Study of the amniotic fluid provides useful information about the well being and also maturity of the fetus. Intra-amniotic instillation of chemicals is used as method of induction of abortion. Excess or less volume of liquor amnii is assessed by amniotic fluid index (AFI) It is measured to diagnose the clinical condition of polyhydramnios or oligohydramnios respectively . Rupture of the membranes with drainage of liquor is a helpful method in induction of labor 11/4/2023

51. THE UMBILICAL CORD: DEVELOPMENT 11/4/2023

52. STRUCTURES Covering epithelium Wharton’s jelly Blood vessels Remnant of the umbilical vesicle (yolk sac) and its vitelline duct Allantois Obliterated extraembryonic coelom 11/4/2023

53. CHRACTERSTICS About 40 cm in length with an usual variation of 30–100 cm. diameter is of average 1.5 cm with variation of 1–2.5 cm. thickness not uniform but presents nodes or swelling at places. These swellings (false knots) may be due to kinking of the umbilical vessels or local collection Wharton’s jelly. True knots (1%) are rare. Long cord may form loop around the neck (20–30%). The umbilical arteries do not possess an internal elastic lamina but have got well developed muscular coat . These help in effective closure of the arteries due to reflex spasm soon after the birth of the baby. Both the arteriesand the vein do not possess vasa vasorum . 11/4/2023

54. ATTACHMENT It usually attaches to the fetal surface of the placenta somewhere between the center and the edge of the placenta—called eccentric insertion . The attachment may be central , marginal or even on the chorion laeve at a varying distance away from the margin of the placenta, called velamentous insertion . 11/4/2023

55. 11/4/2023 PLACENTA USES IN MEDICINE AND COSMETICS

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58. REFRENCES 11/4/2023

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