Undifferentiated stratified epithelium of nasal mucosa

as a universal transitional form of nasal epithelium

in its reparative and pathological regenerations

Olga N. IvanovaInstitute of Sorption and Endoecology Problem

National Academy of Sciences of Ukraine;Institute of Human Ecological Pathology, Kiev, Ukraine

► The role of undifferentiated stratified epithelium in regeneration of nasal mucosa is not sufficiently investigated. This research was focused on nasal epithelial regeneration of patients with chronic rhinitis including that followed from the accident in Chernobyl Nuclear Power Station.

Stratified squamous metaplasia of nasal mucosa in liquidators of Chernobyl accident consequences. Semithin cut, methylene blue and fuchsin, х300.

Fibrovascular papillae of nasal mucosa in liquidators of Chernobyl accident consequences. Semithin cut, methylene blue, х200.

Diagram of reparative and pathological regenerations of nasal epithelium

Formation of3-4-layer

undifferentiated epithelium

(transitional form of nasal

epithelium) Nasal epithelial disregenerationdisregeneration:

cuboidal metaplasia, squamous

metaplasia, formation of fibrovascular

papillae, etc.

Contact inhibition

of epithelial cells and

formation of flattened

cell monolayer

Normalpseudostrati

fied ciliatednasal

epithelium

Damaged nasal

epithelium;

uncovered basal

membrane

Migration of

epithelial cells on

to uncovered basal

membrane

Cell proliferat

ionof wound edge or glands

collector ducts

Acutedamage

Chronicdamage

Material & Methods

Research materialResearch materialClinical group: patients with chronic

rhinitis Nosological

control groupLiquidators of Chernobyl accident consequences

Quantity of patients 40 53Patients mean age (yrs) 42.7±3.9 48.5±1.3

Dose of external irradiation (cSv)

Range – 2–60Mean – 23.8±2.35

Research Research methodsmethods Paraffin cuts Semithin cuts

Survey histological methods

Hematoxylin-eosin; Azure-eosin; Van Gieson method

methylene blue; Hayat method

Selective histochemicalmethods

PAS reaction; Brachet method; congo red; Grimelius method; “latent” metachromasia reaction;

diazo reaction; Shubich method; Weigert method; Mowry method; sudan black by Berenbaum

Mowry method; Grimelius method; Heidenhain's iron hematoxylin and fuchsin

Transmission electron microscopy

Ultrathin cutsdouble contrast study (uranylacetate and lead citrate by Reynolds)

Discussion► In both groups, the successive nidal degeneration, alteration,

necrosis and desquamation of pseudostratified ciliated epithelium and uncovering the basal membrane were observed. Reparative regeneration of epithelial defect commenced with formation of flattened cell monolayer later replaced with 3-4-layer cuboidal transitional undifferentiated epithelium. The latter was replaced with pseudostratified ciliated epithelium if the pathogenic factor had been eliminated. In the case of pathological regeneration (chronic inflammation or strong damaging factor), the undifferentiated stratified epithelium was replaced with stratified squamous metaplasia (SSM), stratified cuboidal metaplasia (SCM), with fibrovascular papillae (FVP).Pathological regeneration of

pseudostratified ciliated nasal epithelium of patients with chronic rhinitis in nosological control group(NCG) and liquidators of Chernobyl accident consequences (LChAC).

– р<0.01; – р<0.001

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**

***

0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

FVP SSM SCM FVP+ SSM +SCM

Part

NCG

LChAC

Reparative regeneration of epithelial defect commenced with formation of flattened cell monolayer. Transmission electron microscopy, х7200.

Epithelial flattened monolayer replaced with 3-4-layer cuboidal undifferentiated stratified transitional epithelium. Transmission electron microscopy, х6500.

In the case of pathological regeneration the undifferentiated stratified transitional epithelium was replaced with stratified squamous metaplasia. Semithin cut, methylene blue, х400.

Acanthocyte of stratified squamous metaplasia of nasal epithelium. Transmission electron microscopy, х3600.

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Regeneration of nasal epithelium in liquidators of Chernobyl accident consequences

Conclusions

► Undifferentiated stratified epithelium Undifferentiated stratified epithelium is is universal universal transitional form transitional form in both in both reparative and pathologicalreparative and pathological regenerations of regenerations of nasal epitheliumnasal epithelium. .

► IfIf the pathogenic factor had been the pathogenic factor had been eliminated eliminated 3-4-layer 3-4-layer cuboidal undifferentiated epithelium cuboidal undifferentiated epithelium was replaced with was replaced with normal pseudostratified normal pseudostratified ciliated ciliated epithelium. epithelium. A similar A similar process is observed after process is observed after mechanical injury of nasal mechanical injury of nasal mucosa and in nasal epithelial differentiation in mucosa and in nasal epithelial differentiation in embryogenesisembryogenesis. . ThereforeTherefore, , reparative regeneration of reparative regeneration of nasalnasal epithelium recapitulates its prenatal development. epithelium recapitulates its prenatal development.

► In the case of chronic or strong damage of In the case of chronic or strong damage of nasal mucosa,nasal mucosa, undifferentiated stratified epithelium undifferentiated stratified epithelium was replaced with was replaced with different different variantsvariants of of metaplasias metaplasias ((pathological pathological regeneration).regeneration).