Transcript Placental Morphology

Placental Morphology Features
1. Placental shape (diffuse, cotyledonary,
zonary, discoidal)
2. Definitive type of placental interface (eg.
epitheliochorial, endotheliochorial,
hemochorial)
3. Fetomaternal interdigitation (folded,
villous, labyrinthe)
4. Fetomaternal blood flow interrelations
(concurrent, countercurrent,
crosscurrent, multivillous)
5. Placental nutrient transport
Wildman D, et al., 2006
Placental structure is highly diverse among mammals
Thornburg and Faber, 1983
hu
^
Thornburg and Faber, 1983
Placental Morphology Features
1. Placental shape (diffuse, cotyledonary,
zonary, discoidal)
2. Definitive type of placental interface (e.g.
epitheliochorial, endotheliochorial,
hemochorial)
3. Fetomaternal interdigitation (folded,
villous, labyrinthe)
4. Fetomaternal blood flow interrelations
(concurrent, countercurrent,
crosscurrent, multivillous)
5. Placental nutrient transport
Wildman D, et al., 2006
The functions of the
placenta are to
establish a dialogue
with maternal
physiology for the
success of pregnancy,
and to provide
nutrients for fetal
growth and
development.
Stroma
Many variations on the
interface can be found
and terminologies
have evolved as
morphological tools
became more
sensitive.
Fetal and maternal blood are
separated by 1 capillary and
(a) fetal epithelium:
Hemochorial placentation
(trophoblasts are directly
exposed to maternal blood;
human, rat, mouse, monkey).
Kaufmann and Burton, 1994
Moffett and Lake, 2006
Placental Morphology Features
1. Placental shape (diffuse, cotyledonary,
zonary, discoidal)
2. Definitive type of placental interface (e.g.
epitheliochorial, endotheliochorial,
hemochorial)
3. Fetomaternal interdigitation (folded,
villous, labyrinthe)
4. Fetomaternal blood flow interrelations
(concurrent, countercurrent,
crosscurrent, multivillous)
5. Placental nutrient transport
Wildman D, et al., 2006
Week 1 of
gestation:
•Trophoblast
differentiation
•Syncytiotrophoblast
differentiation
•Invasion and
formation of the
trophoblastic
shell
•No villous
organization
Benirschke and
Kaufmann, 1999
Villous
Week 2 of
gestation:
•Extravillous
trophoblast
differentiation
•Syncytiotrophoblast
expansion
•Formation of
fetal
vasculature
•Initiation of
villous
organization
Benirschke and
Kaufmann, 1999
Villous placentation
Placentation in primates: spiral artery remodeling
• Rapid invasion of spiral
arteries: endovascular
invasion
• Limited interstitial
trophoblast invasion
• Remodeling of vessel
wall
• Invasion to endometrialmyometrial junction
around 1/3 of gestation
Enders, 2007
CTK IHC
Inappropriate remodelling may lead to hypoxic, nitrative or oxidative
stress and is thought to have clinical significance in adverse pregnancy
outcomes.
Genbacev et. al,
2001
Placental Morphology Features
1. Placental shape (diffuse, cotyledonary,
zonary, discoidal)
2. Definitive type of placental interface (e.g.
epitheliochorial, endotheliochorial,
hemochorial)
3. Fetomaternal interdigitation (folded,
villous, labyrinthe)
4. Fetomaternal blood flow interrelations
(concurrent, countercurrent,
crosscurrent, multivillous)
5. Placental nutrient transport
Wildman D, et al., 2006
Chorionic
plate
Villus
tree
Basal plate
Decidua
Ramsey and Harris, 1966
Adamson et al, 2002
This shows mouse placenta, but the idea of
placental layers in the same for humans and
other primates
Placental Morphology Features
1. Placental shape (diffuse, cotyledonary,
zonary, discoidal)
2. Definitive type of placental interface (e.g.
epitheliochorial, endotheliochorial,
hemochorial)
3. Fetomaternal interdigitation (folded,
villous, labyrinthe)
4. Fetomaternal blood flow interrelations
(concurrent, countercurrent,
crosscurrent, multivillous)
5. Placental nutrient transport
Wildman D, et al., 2006
Blue, red, yellow: type I, II, III stem villi.
Pale blue, violet: terminal villi. These villi are thought to be
the primary sites of nutrient transit to the fetal vessels.
Fuchs and Ellinger, 2004
During pregnancy, there is
thinning of the syncytial layer
and formation of close
association between the basal
syncytium and outer layer of the
villous endothelium. This is
thought to be a major transport
zone.
Fuchs and Ellinger, 2004
Fuchs and Ellinger, 2004
Needed nutrients:
Oxygen, glucose, amino acids, vitamins, ions, minerals,
lipids, water
Potential mechanisms of transit: diffusion, carriermediated transport, vesicular transcytosis