Histology of the Placenta.pptx

Histology of the Placenta

1. Histology of placenta Presenter - Dr. Dirar – R1 Moderator – Dr. Melaku – R3

2. Gross description Development of placenta Histology of placenta Clinical correlation Outlines

3. Gross description Discoid organ 15 to 20 cm in diameter 3 cm thick at the center weighing on average 450 g .

4. two surfaces or plates: the chorionic plate - to which the umbilical cord is attached, and the basal plate - that abuts the maternal endometrium .

5. Cotyledons 15 to 20 lobes, aka cotyledons formed by invaginations of septa from the basal plate

6. Umbilical cord The 50- to 60-cm-long and 12-mm-thick and twisted umbilical cord is attached to the chorionic plate and contains two umbilical arteries and one umbilical vein

7. Development of the placenta

8. Implantation – on decidua functionalis

9. The wall of maternal blood vessels is infiltrated and ruptured by trophoblast cells. And then maternal blood is released into the intervillous space , The uterine spiral arteries are converted to uteroplacental arteries Preeclampsia occurs when there is a reduced development of the branches of the chorionic villus tree and limited fetal growth.

10. The decidual reaction provides an immune protective environment for the development of the embryo production of immunosuppressive substances Syncytiotrophoblast cells do not express major histocompatibility complex class II .

11. Histology

12. Placental lobe - cotyledons

13. cytotrophoblast a layer of mitotically active cells immediately around the amnion and yolk sac nuclei are more round and open

14. syncytiotrophoblast more superficial, no mitotis mass of multinucleated cytoplasm which invades the surrounding stroma possesses a brush border with microvilli

15. Intermediate trophoblast – pleomorphic and hyperchromatic nuclei with amphophilic to eosinophilic cytoplasm Other cell types mesenchymal cells fibroblasts, myofibroblasts , smooth muscle cells Hofbauer cells

16. Early placenta

17. Compared with early placenta, in late placenta Average villous diameter is much smaller Reflecting the extensive branching growth of the villi

18. Late placenta

19. placental barrier consists of Syncytiotrophoblast inner cytotrophoblast layer Basal lamina of the trophoblast Connective ( mesenchymal ) tissue of the villus Basal lamina of the endothelium Endothelium of the fetal placental capillary in the tertiary villus

20. Umbilical arteries Vs. umbilical vein

21. Umbilical arteries Vs. umbilical vein

22. Three regions of the decidua The decidua basalis The decidua capsularis The decidua parietalis chorion laeve Vs chorion frondosum

23. The fetal membranes

24. Chorioamnionitis Complete mole Partial mole Invasive mole Choriocarcinoma Clinical correlation

25. Chorioamnionitis A collection of neutrophils (pus) has formed between the amnion and chorion Inflammation in the decidua (oval) may be physiologic and is not sufficient to diagnose chorioamnionitis

26. Complete mole Diploid gestation with two paternal genomes no identifiable embryo, cord, or amniotic membranes a ‘bunch of grapes ’

27. Marked trophoblastic hyperplasia and vesicular swelling circumferential but haphazard arrangement around the individual villi Vessels seem absent or very scanty

28. Partial mole Triploid Embryo is present

29. grossly vesicular villi are mixed with normal-appearing ones Trophoblastic proliferation is present but lesser than complete mole

30. Invasive mole villi penetrate deeply to the myometrium and/or its blood vessels nearly always of the complete type but occasionally of the partial type

31. Choriocarcinoma Most cases occur following a complete hydatidiform mole characteristically forms soft, dark red, hemorrhagic, round nodular tumor masses

32. clusters of cytotrophoblast separated by streaming masses of syncytiotrophoblast characteristic dimorphic plexiform pattern Villi are characteristically absent

33. Reference Wheater`s functional histology 6th ed Histology - A text and atlas 7th ed. Difiore`s atlas of histology 12th ed. Rosai and Akerman surgical pathology Gabbe text book of obstetrics