Publication: A three-dimensional study of human fetal endocervix with special reference to its epithelium
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Date
1998
Authors
Barberini, F. ; Makabe, S. ; Motta, P.M.
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Publisher
Murcia : F. Hernández
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DOI
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info:eu-repo/semantics/article
Description
Abstract
The development of human fetal cervix has
been systematically studied by SEM, obtaining a
detailed map of its fine structure, particularly concerning
the differentiation and maturation of the endocervical
epithelium, including its "eversion" and "squamous
metaplasia", normally occurring in postnatal life, but not
yet observed in detail by electron microscopy in the
fetus. Cervices from spontaneous abortion at 12, 15, 18,
20, 21 and 22 weeks and from intrauterine fetal death
(hydrocephalus) at 31 weeks of development have been
examined. At 12-15 weeks, as the canalization of the
cervix proceeded, the endocervical epithelium consisted
of high polyhedral cells, with regularly flattened or
concave apices exhibiting scarce microvilli and often
single primary cilia. Some narrow intercellular
infoldings probably corresponded to primordial tubular
glands. At the 18th week the epithelium was made up of
a mosaic of flat or slightly raised polygonal cells, whose
apical surface showed thin microplicae. At the 20th
week a pseudostratified epithelium with many apically
convex cells lined the cervical canal and the tubular
glands. At 21 and 22 weeks "plicae palmatae"
developed, covered by cells, often showing a smooth
central area surrounded by microvilli, provided with a
primary cilium and swollen by secretory material. This
also formed rounded masses on the epithelium. In the
lower part of the endocervix some very elongated cells
showed short microplicae resulting from fusion of microvilli. At the 31st week secretion increased and its
products spreading from the bottom of the glands
contacted isolated ciliated cells at their openings and
diffusely covered the surface epithelium. Most of the
ectocervix exhibited squamous elements, with welldeveloped
labyrinthine microplicae. These cells could
overlap each other and also desquamate. The zone of the
portio vaginalis around the OS of the cervical canal
appeared infolded and hypertrophic. Here, an indented
squamo-columnar junction between the ectocervical and
endocervical epithelium, caused by tongue-like prolongations of squamous epithelium directed toward
the endocervix, was found. Their tips consisted of
elongated cells, rich only in short microvilli.
Our data indicate that the features of the microvillous
cells are an expression of a hormone-dependent
differentiative process. Thus, their secretion might be
stimulated by progesterone. Similarly microplicae on the
ectocervical epithelium (a sign of squamous maturation)
might be promoted by estrogens. Furthemore, two
aspects were significative: 1) the finding - in an early
phase only (18th week) - of endocervically-located
squamous cells, although devoid of microplicae; and 2)
the occurrence - in the latest phase (31st week) - of an
indented squamo-columnar junction on the surface of the
portio. These features are in agreement with the caudal
shift of the squamo-columnar junction near the uterine
cavity to the ectocervix after cervico-vaginal
demarcation; the squamous metaplasia of this everted
endocervical epithelium has been reported by some
authors. It is likely that these processes, occurring in
fetal life as well as in pregnant women, are related to a
common hormonal background, arising from the mother
to her fetus.
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