الفهرس 
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Abstract
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Summary
The aim of this investigation was to study the potential impacts of oral administration
of silver nanoparticles on the mucous membrane and salivary glands of the tongues of
albino rats and the possibility of one month recovery period.
Forty-six adult male albino rats with an average 150-180 gram body weight were
used in the present investigation. They were divided into the following groups:
group 1: consisted of 15 rats, they received 10mg/kg b.w/day AgNP solution
with particle sizes ranging from 3 to 20 nm per os using curved metallic oropharyngeal tube for 21 days.
group 2: consisted of 15 rats, they were treated the same way as group 1 for 21
days then left for 1 month as a recovery period without treatment.
group 3: consisted of 16 rats, served as controls. They were subdivided into
two subgroups:
Subgroup 3.1 consisted of 8 rats, they received deionized water per os using
metallic curved oro-pharyngeal tube for 21 days.
Subgroup 3.2 consisted of 8 rats, they were treated the same way as subgroup
3.1 and then left untreated for one more month.
The experiment lasted for 21 days for group 1 and 3.1 then the rats were
euthanized by cervical dislocation. While the rats of group 2 and 3.2 were euthanized the
same way after one month of stopping treatment for recovery; their tongues were
dissected out, fixed in 10% neutral buffered formalin, processed, embedded in paraffin
and sectioned to be stained with:
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Hematoxylin and eosin for detection of any possible structural changes in the
mucous membrane and salivary glands of the tongues.
Mouse monoclonal antibody for localization of PCNA to detect any possible
changes in its index.
Representative tongue specimens from the different groups were fixed in
glutaraldehyde (3%), dried in a desiccator under vacuum, gold sputtered to be examined
with the scanning electron microscope to detect any possible ultrastructural changes in its
dorsal surface.
Results:
I. Histological Results: (Haematoxylin and Eosin stain)
The histological examination of the mucous membrane of the tongue of the control
rats showed the normal histological features of surface epithelium and underlying
lamina propria.
Filiform papillae appeared sharp conical and the fungiform papillae appeared
rounded, mushroom like with flattened top and a single well developed taste pore at the
middle of the superior surface of each papilla, well-formed connective tissue in the
lamina propria. The circumvallate papilla was surrounded with a circular furrow.
At the bottom of the furrow opened the ducts of pure serous salivary glands situated
beneath the circumvallate. They were formed of normal serous acini and ducts. Pure
mucous salivary glands were also seen among the lingual muscle fibers posterior to the
pure serous glands. They were formed of normal mucous acini and ducts.
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Those treated with AgNPs revealed atrophic and degenerative changes that
involved the surface epithelium and lamina propria of both the dorsal and ventral
surfaces of the tongue as well as the lingual salivary glands.
The filiform papillae were markedly atrophic, their number and height were
apparently much decreased. The fungiform and circumvallate papillae showed signs of
atrophy and shrinkage. Taste buds appeared vacuolated, shrunken, partially lost their cells
or completely absent. Also the lingual glands suffered intracytoplasmic vacuolization of
the serous acini and cystic transformation of the mucous acini.
Examination of the tongues of the rats which were allowed a recovery period for
one-month showed improvement in the histological picture of the surface
epithelium and lamina propria of the dorsal and ventral surfaces of their tongues as
well as their lingual salivary glands.
There was regain in the number and height of the filiform papillae. The fungiform and
circumvallate papillae appeared more or less normal without signs of shrinkage or
degeneration. The taste buds got regenerated and appeared more or less normal.
The lamina propria regained the density and arrangement of its collagen fibers with the
presence of a lot of blood vessels. Remaining inflammatory cell infiltrate was sometimes
encountered. The serous and mucous acini of the lingual glands showed improvement of
their histological architecture.
II. Immunohistochemical results: (Proliferating Cell Nuclear Antigen)
The histological sections of tongues of the control animals (group 3.1, 3.2)
presented strongly positive PCNA staining reaction mainly at the basal and
parabasal cells of the surface epithelium indicating normal proliferation of the cells
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of the dorsal and ventral surfaces of the tongue. All the basal cells were strongly
positively stained.
While the sections of the tongues of AgNPs treated rats showed low expression of
PCNA in the basal layer of the epithelium of the dorsal and ventral surfaces of the
tongue ranging from negative to weakly positive staining reaction which indicated
a decrease in proliferation of basal and parabasal cell layers denoting marked
decrease in the rate of turnover and cell renewal. Most of the basal cells were
negatively stained.
The sections of the tongues of rats that allowed a recovery period for one-month
after 21 days’ treatment with Silver nanoparticles, showed moderately to strongly
positive PCNA expression in the basal and parabasal cells of the dorsal and ventral
surfaces of the tongue
III. Scanning Electron Microscopic results:
The dorsal surface of the tongue of the control groups was mainly covered with long
and conical filiform papillae with uniform keratinized tips arranged in parallel regular
rows. Scattered fungiform papillae with broad apices were seen among numerous filiform
ones. Thin epithelial smooth cells were depicted around centrally located well defined
regular gustatory pore surrounded by shallow indentation. Oval or rounded circumvallate
papilla was found; situated symmetrically and obliquely to the median line of the tongue.
The body of the papilla was limited by a deep circular sulcus.
The dorsal surface of the tongues of rats which were exposed to administration of
silver nanoparticles solution in a dose 10 mg/kg revealed numerous filiform
papillae with evidently disturbed orientation and inclination. They showed an
apparent decrease in number, change in distribution and became thinner having
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more slender shape than a conical one with abnormal extreme bending or
sometimes looping.
The fungiform papillae showed marked decrease in their size, lost their characteristic
mushroom shape and revealed ill-defined or obliterated taste pores. The circumvallate
papillae appeared shrunken with marked reduction of their size with shallowing or even
loss of their furrows.
The dorsal surface of the tongues of rats which were allowed one month recovery
period showed improvement under the (SEM) when compared to rat’s tongue
treated with AgNPs.
The overall morphology of the dorsal surface of the tongue showed almost normal
distribution of the papillae. Filiform papillae facing same direction and fungiform
papillae between them. However, some of the filiform papillae still suffered signs of
destruction.
The fungiform papillae showed almost normal appearance. Taste pores were obvious
on the surface of the fungiform papillae along with some scaling cells at higher
magnification. The circumvallate papillae also looked normal. Each papilla had a circular
form with a furrow around