The fetal development of the human uterine cervix from the 12th to the 31st postmenstrual week as revealed by scanning electron microscopy. Anatomical and clinical correlations.
To clarify the differentiation of the human uterine cervix, fetuses of the 12th, 15th, 18th, 20th, 21st, 22nd, and 31st postmenstrual week were studied by Scanning Electron Microscopy. At the 12th week the endocervical epithelium consisted of microvillous cells, often showing single cilia and anlages of tubular glands. At the 15th week the cervical canal was entirely formed and its surface cells appeared columnar. At the 18th week these cells were replaced by flat or slightly raised cells, provided with thin microplicae. At the 20th week the endocervical epithelium appeared pseudostratified with higher, apically-convex and shorter basal cells; glands developed in form of tubular invaginations of the luminal epithelium. At the 21st week in the lower part of the endocervix polymorphic, globose cells with short and stubby microvilli and others elongated, having short microplicae, were observed. These latter likely corresponded to the so-called columnar cells undergoing squamous metaplasia. Among microvillous and/or metaplastic cells, a number of apoptotic cells, as globose elements with a ruffled and invaginated surface, were also noted. At the 22nd week evident plicae palmatae were found, covered by microvillous secreting cells. These showed smooth bulged apices releasing droplets by a "micro-apocrine" mechanism. These features increased at the 31st week, when many droplets were noted also around the mouth of the cervical glands. Only at this phase of development fully ciliated cells were found often contacting secretory material. Mature squamous exfoliating cells with complex microplicae covered an hypertrophied portio vaginalis. The squamous cells extended toward a squamo-columnar junction in form of flat, tongue-like projections. Their tips consisted of immature squamous metaplastic cells, which were endocervical columnar progressively becoming elongated elements, exhibiting short microvilli. The above features are rather similar to those occurring during the adult reproductive age. Therefore, it might be hypothesized that, during pregnancy, a common gestational hormonal background may induce somewhat similar morpho-dynamic processes in the cells and tissues of the fetal reproductive tract mimicking what occurs in the adult female.
Barberini
F
F
Department of Human Anatomy, University of Rome La Sapienza, Italy.
Makabe
S
S
Correr
S
S
Motta
P M
PM
D002584:Cervix Uteri / Q000196:embryology* / Q000648:ultrastructure; D004848:Epithelium / Q000196:embryology / Q000648:ultrastructure; D005260:Female; D005865:Gestational Age; D006801:Humans; D008855:Microscopy, Electron, Scanning; D008871:Microvilli / Q000648:ultrastructure; D011247:Pregnancy