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UDK: 61/616-091.8
COMPARATIVE MORPHOLOGICAL AND MORPHOMETRIC INDICATORS OF
MAJOR SALIVARY GLANDS UNDER CHRONIC EXPOSURE TO GAS
Usmonov Sojiddin Saloxiddinovich, Namazov Farrux Jumayevich
Abstract:
This scientific study investigates morphological and morphometric changes in the
major salivary glands of laboratory animals under chronic exposure to NO₂ and SO₂ gases.
The histological structure of the parotid, submandibular, and sublingual salivary glands was
analyzed using microscopic and morphometric methods. The results revealed cellular and
tissue-level degeneration, inflammation, atrophic changes, and a decrease in secretory
activity. These changes reflect the adverse effects of the gas mixture and emphasize the need
for preventive measures to ensure environmental safety.
Introduction
In recent years, the increase in industrialization and vehicle emissions has led to a serious
problem of atmospheric air pollution. Among the gaseous pollutants, nitrogen dioxide (NO₂)
and sulfur dioxide (SO₂) are known to negatively affect the respiratory tract and oral tissues.
However, the effects of these gases on the salivary glands—especially the major ones
(parotid, submandibular, and sublingual)—at morphological and morphometric levels have
not been sufficiently studied.
Salivary glands play a vital role in maintaining oral hygiene and providing immunological
protection. Therefore, studying their condition under chronic gas exposure is essential. This
study aims to determine the morphological and morphometric changes in major salivary
glands under chronic gas exposure and compare them with a control group.
Materials and Methods
Study Subjects
The experiment involved 30 healthy, sexually mature male Wistar rats (weighing 180–220
g), divided into two groups:
Control group (n = 15):
Maintained under standard laboratory conditions.
Experimental group (n = 15):
Exposed to a mixture of NO₂ and SO₂ gases at 0.2
ppm concentration for 6 hours daily over 90 days.
Sample Collection
At the end of the experiment, the animals were euthanized under anesthesia. The parotid,
submandibular, and sublingual salivary glands were harvested and fixed in 10% neutral
formalin. The samples were embedded in paraffin, sectioned at 5 μm thickness, and stained
with hematoxylin and eosin for microscopic examination.
Morphometric Analysis
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After microscopic imaging, the following parameters were measured using the ImageJ
software:
Acinus diameter (μm)
Nuclear volume (μm³)
Number of secretory cells
Capillary density (per 100 μm²)
For each sample, average values were calculated based on 10 visual fields.
Statistical Analysis
Data were presented as mean ± standard deviation (M ± SD). Differences between groups
were analyzed using Student's t-test (p < 0.05 was considered statistically significant).
Results
Morphological Changes
Parotid Gland:
In the control group, parotid glands showed a normal architecture with densely packed acini
and minimal stromal tissue. In the experimental group, cytoplasmic vacuolization, nuclear
pyknosis, and disappearance of secretory granules were observed. Lymphocytic infiltration
and partial fibrotic changes were noted in the stroma.
Submandibular Gland:
A reduced number of acini, varying degrees of cellular degeneration, stromal fibrotic growth,
and microcirculatory disturbances were seen in the experimental group. This gland showed
the highest sensitivity to gas exposure.
Sublingual Gland:
Secretory epithelial cells showed nuclear deformation, vacuolization, and necrotic signs.
Inflammatory signs were detected around blood vessels in the stroma.
Morphometric Indicators
Indicator
Control Group (M
± SD)
Experimental Group (M
± SD)
Difference
(%)
p-
value
Acinus
diameter
(μm)
56.2 ± 3.1
42.8 ± 2.7
−23.9%
<0.01
Nuclear
volume
(μm³)
112.5 ± 5.4
89.3 ± 4.9
−20.6%
<0.01
Capillaries (per 100
μm²)
7.4 ± 0.8
5.1 ± 0.7
−31.1%
<0.01
Secretory
cells 34.5 ± 2.6
25.2 ± 2.1
−27.0%
<0.01
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Indicator
Control Group (M
± SD)
Experimental Group (M
± SD)
Difference
(%)
p-
value
count
These findings demonstrate that chronic exposure to NO₂ and SO₂ gases significantly alters
the structural integrity of major salivary glands. The parotid gland showed cytoplasmic
vacuolization and granule loss; the submandibular gland exhibited fibrotic overgrowth and
degeneration; the sublingual gland showed necrotic changes. These changes are likely due to
disruptions in cellular metabolism, oxidative stress, and impaired microcirculation.
Morphometric changes serve as objective markers of functional impairment—reduced
secretory cell count and nuclear volume indicate decreased secretory activity. The
submandibular gland appeared to be the most sensitive among the three.
Conclusion
Chronic exposure to gas mixtures causes significant morphological and morphometric
changes in the major salivary glands. These changes adversely affect the overall health of
the organism and oral cavity function. The results emphasize the importance of
environmental pollution control and the implementation of preventive public health
measures.
References
1.
Abdullayev, A.Sh., & Karimov, J.B. (2018).
The effects of atmospheric gases on the
organism
. Tashkent: Fan va texnologiya Publishing.
2.
Otabekov, A.T., & Raximov, Z.Z. (2020). Morphological features and pathology of
salivary glands.
Scientific Journal of Tashkent Medical Academy
, 3(45), 67–73.
3.
Park, Y., et al. (2019). Effect of nitrogen dioxide on salivary gland morphology in
rats.
Journal of Toxicologic Pathology
, 32(4), 287–295.
https://doi.org/10.1293/tox.2019-
4.
World Health Organization (WHO). (2018). Ambient air pollution: Health impacts.
https://www.who.int/news-room/fact-sheets/detail/ambient-(outdoor)-air-quality-and-health
5.
Ganiev, B.O., & Tursunov, M.R. (2017). The dependence of salivary gland activity
on ecological factors.
Uzbekistan Medical Journal
, (2), 44–48.
6.
Sun, H., et al. (2021). Chronic exposure to sulfur dioxide causes salivary gland
dysfunction via oxidative stress mechanisms.
Environmental Science and Pollution
Research
, 28(16), 19911–19919.
https://doi.org/10.1007/s11356-020-11909-x
7.
Mahkamov, F.M. (2015).
Morphological indicators of the div’s response to
ecological stress
. Tashkent: Academy of Sciences of the Republic of Uzbekistan.
8.
Zhang, Q., et al. (2016). Air pollution and salivary antioxidant system alteration.
Environmental Research
, 146, 218–226.
https://doi.org/10.1016/j.envres.2016.01.019
9.
Sirojiddinov, A.S., & Karimova, L.U. (2019). Morphology and functional
significance of salivary glands.
Problems of Medicine and Biology
, (1), 51–57.
Kuo, Y.C., et al. (2020). Long-term effects of air pollutants on oral tissues: A histological
study.
Toxicology Letters
, 331, 1–7.
