Histology of the Placenta

1. HISTOLOGY OF
PLACENTA
Presenter - Dr. Dirar – R1
Moderator – Dr. Melaku – R3

2. 1. Gross description
2. Development of placenta
3. Histology of placenta
4. 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

12.  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.

13. The decidual reaction
 provides an immune
protective
environment for the
development of the
embryo
1. production of
immunosuppressiv
e substances
2. Syncytiotrophoblas
t cells do not
express major
histocompatibility
complex class II.

14. Histology

15. Placental lobe - cotyledons

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

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

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

19. Early placenta

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

21. Late placenta

22. 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

23. Umbilical arteries Vs. umbilical vein

24. Umbilical arteries Vs. umbilical vein

25. Three regions of the decidua
1. The decidua basalis
2. The decidua
capsularis
3. The decidua
parietalis
 chorion laeve Vs

26. The fetal membranes


27. 1. Chorioamnionitis
2. Complete mole
3. Partial mole
4. Invasive mole
5. Choriocarcinoma
Clinical correlation

28. 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

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

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

31. Partial mole
 Triploid
 Embryo is present

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

33. 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


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

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

36. 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