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syncytiotrophoblast

Syncytiotrophoblast is a multinucleated, continuous layer that forms the outer surface of the placental chorionic villi. It arises from the fusion of underlying cytotrophoblast cells during early placental development, creating a single syncytial epithelium that covers the villous core.

Location and structure: The syncytiotrophoblast lines the villous surface and is in direct contact with maternal

Functions: It is a major site of placental hormone production, secreting human chorionic gonadotropin (hCG), human

Development and turnover: Cytotrophoblasts proliferate and fuse to replenish the syncytial layer throughout pregnancy. Structural features

Clinical relevance: Abnormal syncytiotrophoblast formation or turnover is linked to placental pathologies such as preeclampsia and

blood
in
the
intervillous
space.
It
presents
microvilli
on
the
fetal-facing
side
to
enhance
exchange
and
lacks
distinct
cell
boundaries,
forming
a
seamless
barrier
that
regulates
transfer
of
gases,
nutrients,
and
waste.
placental
lactogen
(hPL),
estrogens,
and
progesterone
precursors.
The
layer
participates
in
nutrient
and
gas
exchange
between
mother
and
fetus
and
contributes
to
maternal
immune
tolerance,
in
part
through
expression
of
nonclassical
HLA-G
molecules.
It
also
interacts
with
extravillous
trophoblasts
to
remodel
maternal
spiral
arteries
and
maintain
placental
perfusion.
of
the
layer
change
over
gestation,
including
the
formation
of
syncytial
knots
and
remodeling
of
surface
microstructures.
intrauterine
growth
restriction.
Assessments
of
placental
hormones
and
trophoblast
turnover
markers
can
inform
evaluations
of
placental
function.