1. The Human Placenta
Georgia Duker, Ph.D.

2. Lecture Outline Placental Functions Placental Development Implantation
Mature Villus Structure
Fetal Membranes
Placental hormones

3. Placental Functions

4. Gas Exchange Bronchus

5. Skin – Protection & Heat Exchange

6. Corpus Luteum – Endocrine

7. Intestine – Nutrient Absorption

8. Kidney – Waste Removal

9. The Conceptus

11. Pituitary hormones
Ovarian hormones
Ovarian cycle
Uterine cycle

12. Implantation - Attachment

13. Implantation - Attachment

14. Implantation Invasion
Endometrial epithelial
desmosomes weaken
Syncytiotrophoblasts
Proteases, MMPs
Vascular adhesive integrins
Immune modulation
hCG – progesterone continuation
Invasion depth
Decidua - remodeled

15. Implantation – Proliferation of Chorionic Plate

16. Implantation – Proliferation 1o Chorionic Villi
day 12-15
Outer syncytiotrophoblasts
Inner core cytotrophoblasts
Lacunae

17. Implantation – Proliferation 2o Chorionic Villi
day 15-21
Syncytiotrophoblasts
Cytotrophoblasts
Anchor villi to decidua
Extraembry mesoderm
Implantation – Proliferation 2o Chorionic Villi

18. Implantation – Proliferation 3o Chorionic Villi
Day 18-term
Syncytiotrophoblasts
Cytotrophoblasts
Mesoderm
Fetal blood vessels
Implantation – Proliferation 3o Chorionic Villi

19. 3o Villus Maturation
1st Trimester
2nd Trimester
3rd Trimester

20. 1st Trimester 3rd Trimester

21. Final Diffusion Barrier

22. Final Diffusion Barrier

23. Placental Villous Tree Structure

24. Placental Villous Tree Structure

25. Placental Villous Tree Structure
cotyledon

26. Cotyledons

27. Placental Villous Tree Structure

28. Decidua Basalis

29. Placental Villous Tree Structure

30. Maternal Fetal Hemoglobin

31. Placental Villous Tree Structure

32. Uterine/placental Blood Flow
Cytotrophoblasts remodel uterine spiral arteries
Maternal blood flow regulated by:
Cytotrophoblast shell
Vascular smooth muscle

33. Remodeling of spiral arteries during normal pregnancy
Hoang et al., Biochemistry 40 (2001), pp. 4077–4086.

34. Remodeling of spiral arteries during normal pregnancy
Poiseuille’s law of fluid flow in a cylinder reveals that flow is proportional to the radius to the fourth power. Therefore, doubling the radius of a uterine vessel will increase the flow 16 times. Comparison of vessels in the nonpregnant uterus to those at term in normal pregnancy reveals that these vessels can increase their radii by as much as ten fold and therefore may increase blood flow by as much as a factor of 10,000.
Spiral Arteries (non-pregnant)
Spiral Artery (pregnant)

35. Preeclampsia and IUGR (shallow placentation)
Occur 3-5% of pregnancies

37. Fetal Membranes

38. Fetal Membranes

39. Placental Transport Mechanisms
Gases
Passive diffusion
IgG
Receptor-mediated endocytosis
Ions
Active transport ATP-pumps
Glucose
Facilitated diffusion
Amino acids
LDL
pathogens
Alcohol, drugs, bacteria, viruses

40. Placental Hormone Production
Syncytiotrophoblasts
Human chorionic gonadotropin
Human placental lactogen
Progesterone
Estrogen
Decidua
Prolactin
Relaxin
Prostaglandins (limited)
Implantation site/time
Partuition

41. The Human Placenta
Georgia Duker, Ph.D.

42. Remodeled Spiral Arterioles

43. Adrenal Cortex – Endocrine Gland