The human umbilical cord is not covered by a single layer but a distinctive multilayered epithelium

2nd International Histology and Embryology Congress, Sakarya, Türkiye, 26 - 28 Eylül 2024, ss.60-61, (Özet Bildiri)

THE HUMAN UMBILICAL CORD IS NOT COVERED BY A SINGLE LAYER

BUT A DISTINCTIVE MULTILAYERED EPITHELIUM

EZEL ERKAN1 | BİLGE SERDAROĞLU1 | İBRAHİM ALPTEKİN1 | DİLEK ŞAHİN2 |

DERYA UYAN HENDEM2 | FERDA TOPAL .ELİKKAN1 | ALP CAN1

1 Laboratory For Stem Cells And Reproductive Cell Biology, Department Of Histology And Embryology, Ankara

University School Of| 2 Perinatology Clinics, Obstetrics And Gynecology Department, Ankara Bilkent City

Hospital | ezelerkan@gmail.com

Abstract

Introduction: The placenta, umbilical cord (UC), and associated amniotic membranes are

typically regarded as residual organs of parturition and are discarded after birth. Despite

having reached the final stages of differentiation, these are significant interest due to the

presence of epithelial and mesenchymal cellular components.The epithelial tissue that covers

the UC is typically referred to as the 'umbilical cord epithelium' or 'cord lining' in previous

studies. These terms refer exclusively to the surface epithelium sheath. It is therefore more

informative to use the term 'umbilical cord epithelium' (UCE) in order to distinguish it from

its placental counterpart, as opposed to simply referring to it as amniotic epithelium.In the

period following the historically significant articles, only a few more from the 1980s to the

early 2000s have concentrated exclusively on the tissue specimens. The objective of these

studies was to assess the distribution of cytoskeletal and cornified epithelial cell-specific

proteins. More recently, some stem cell markers have been investigated in this relatively

unidentified epithelial tissue.

Objective: The objective of this study is to provide a detailed description of the distinct

structural characteristics and the abundance of specific proteins in this unique UCE, many of

which have not yet been demonstrated in previous studies.

Material – Method: UCs were obtained by Caesarean section, approximately 20 cm away

from the umbilicus, specifically from the proximal one third of the cord. Samples were placed

in appropriate fixatives for examination under light, transmission and scanning electron

microscopes. Toluidine blue stained semi-thin sections and periodic acid-Schiff stained and

hematoxylin-eosin stained cryosections were examined under light microscope. Several

cytoskeletal, basement membrane and junctional proteins immunofluorescence (IF) stained

and observed by super-resolution confocal microscopy.

Results: UCE displayed a range of stratification, ranging from a single squamous layer to 4-5

layers of round/cuboid cells, challenging the notion of considering it as a single-layered

structure. During TEM observations of control cords, it was noted that the outer lining of the

cords exhibited distinctive features that could not be classified among the known epithelial

types due to the high degree of variability observed. Moreover, our IF findings have revealed

several distinctive structural features and provided detailed insights into selected in situ

protein distributions.

Conclusion: Our study offers a comprehensive overview of the human UCE. It is not accurate

to consider UCE as representing a single or stratified epithelial form. It constitutes a discrete

entity, exhibiting a thickness of between two and five layers, situated in close proximity to the

continuous basal membrane.

This study received partial funding from T.BİTAK 121S821 and the Ankara University

Scientific Research Fund TSG-2020-2545.