الفهرس 
Development of GonadsOnly 14 pages are availabe for public view
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Abstract
The present study investigated and compared the
effect of noise stress exposure on the testis and the ovary of
albino rats at three critical periods of life; the prenatal, prepubertal
and adult stages. The aim was to reveal the most
susceptible period of lifetime during which these organs are
prone to injury.
Seventy two albino rats (36 males and 36 females) of
Wistar strain were used in the study. The experimental
groups were exposed to noise at an intensity of 100 dB for
a period of 6 hours daily from 8am to 2pm o’clock for all
groups. Pregnant mothers were exposed to noise stress for
12 days (from day 8 – day 20 of gestation) then fetuses
were extracted while pre-pubertal (aged 3weeks) and adult
(aged 3 months) rats were exposed to noise stress for 4
weeks. Rats were assigned to 12 groups (each containing 6
rats); both control and experimental.
At the end of the experiment, all animals; control and
those exposed to noise (20 days old fetuses, 7 weeks old
rats and 4 months old rats) were sacrificed using over dose
of ether inhalation. The testes and ovaries of all rats were
collected. The specimens were processed for paraffin block
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embedding and stained with standard histological stains
(Hx&E, PAS and Masson’s Trichrome) for light
microscopic examination. Immunohistochemical staining
for apoptosis was performed on paraffin sections utilizing
TUNEL assay. Histomorphometric analysis was performed
utilizing image analysis software and results were subjected
to statistical analysis using ANOVA test.
Regarding the testis, the three age control groups
showed histological differences. The tunica albuginea
increased in thickness in contrast to tunica vascuolsa
which diminished in thickness as age advanced. Size of the
seminiferous tubules increased with age. Regarding the
germinal epithelium, the testes of 20 days old rat fetuses
was composed only of two types of cells; the gonocytes and
the supporting cells. In the 7 weeks old rats, the germinal
epithelium was formed of several cell types;
spermatogonia, the spermatocytes, the round immature
spermatids. Few elongated mature spermatids were
detected in this age group. Regarding the 4 months old
group, the germinal epithelium was formed of
spermatogonia, spermatocytes, round spermatids and
elongated spermatids, arranged in that order from the basal
compartment to the adluminal compartment. Sertoli cells
were more detected in the adult group compared to the 7
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weeks old rats. The interstitial cells of Leydig increased in
number as age advanced.
Examination of the testes of 20 days old albino rat
fetuses whose mothers were exposed to noise revealed that
the tunica albuginea was apparently thicker than the control
group and the tunica vasculosa was also formed of less
densely arranged loose connective tissue compared to the
control group. Seminiferous follicles were gathered into
clusters and their size decreased compared to the control
group. The supporting cells were detached from the
basement membrane and were closely packed with
pyknotic nuclei. The gonocytes also showed pyknotic
nuclei with vacuolated cytoplasm compared to the control
group.
Examination of testes of the 7 weeks old albino rats
which were exposed to noise, at the age of 3 weeks for one
month, showed the presence of localized thickening of
tunica albuginea and increased thickness of tunica
vasculosa. Size of seminiferous tubules was smaller
compared to the control group. Some areas showed wide
separation of the tubules from the capsule. Most of the
tubules showed rupture of their basement membranes. The
spermatogenic cells lining the tubules showed pyknotic
nuclei with massive cytoplasmic vacuolation while others
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were exfoliated into the lumen. Some Sertoli cells also
showed pale staining of their nuclei. Interstitial cells of
Leydig had dark nucleus with presence of congested blood
vessels in some interstitial tissue spaces. The most
characteristics observation was retardation of development
of seminiferous tubules. This could be detected by the
absence of mature spermatids which were detected in the
control group.
Examination of testes of 4 months old albino rats
exposed to noise revealed relative thinning of tunica
albuginea and thickening with congestion of blood vessels
in tunica vascuolsa compared to control group. The
seminiferous tubules were reduced in size. Various forms
of affection of the spermatogenic cells lining the
seminiferous tubules were seen ranging from extreme
thinning out of the epithelium in some locations to patches
of focal degeneration or exfoliation into the tubular lumen.
Spermatogonia, spermatocytes and spermatids showed
fusion of their cell membranes, cytoplasmic vacuolation,
nuclear disintegration and cellular necrosis. Some Sertoli
cells also showed faint stained degenerated nuclei while
others were unaffected. Most of the interstitial cells of
Leydig showed faint staining of their nuclei. Few of them
showed small dark nuclei.
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Regarding the ovary, the three age control groups
showed histological differences. The size of the ovary
increased as age advanced. The ovary was surrounded by
surface epithelium which in the prenatal group was
multilayered while it was single in the 7 weeks old rats and
adult groups. As for the types of follicles, in the 20 days
old fetuses, different types of structures were observed.
Some oocytes were devoid of cell boundaries and were
packed together in pockets surrounded by connective tissue
collagen fibers. Other oocytes acquired cell boundaries and
were arranged in groups mainly in the peripheral part of the
ovary. Darker cells were seen scattered in between the
oocytes. In some areas, one or two of these cells were
observed attached to the cell membranes of the oocyte. In
some sections, oocytes were observed surrounded by a
single layer of flattened cells. In the core, some of the
oocytes were seen surrounded by cuboidal cells changing
them into follicle-like structures. In the 7 weeks old group
there were primordial follicles, primary, secondary, tertiary,
Graafian follicles with apparent predominance of the
secondary follicles. Corpus luteum was occasionally
detected in the examined sections. In the 4 months old
group, the same types of follicles of the previous group
were noticed. Corpora lutea increased in number compared
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to the younger age. Regarding the medulla, it became more
distinct with advancement of age.
On examination of ovaries of the 20 days old albino
rat fetuses whose mothers were exposed to noise, the
ovarian surface epithelium showed focal areas of increased
thickness. The ovarian tissue showed shrunken follicle-like
structues. The oocytes showed dark stained cytoplasm and
pyknotic nuclei. Also the surrounding pregranulosa cells
had pyknotic nuclei. The observed different structures in
the control group could not be deteceted in the
experimental group.
Examination of ovaries of the 7 weeks old albino
rats which were exposed to noise, at the age of 3 weeks for
one month, showed that the ovary was apparently
decreased in size. There was apparent reduction in the
number of follicles. Graafian follicles and corpus luteum
were not detected in the examined sections. The oocytes
either showed dark stained cytoplasm or vacuolated one
with small pale stained or shrunken pyknotic nuclei. The
surrounding granulosa cells showed marked vacuolation of
the cytoplasm and completely degenerated nuclei. Neither
Graafian follicle nor corpus luteum could be detected in the
examined sections.
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Examination of ovaries of 4 months old albino rats
exposed to noise showed apparent shrinkage in the size of
the ovary with apparent decrease in the number of follicles.
The ovary showed marked predominance of the atretic
follicles and corpora lutea as compared to the control
group. The medulla showed deeply stained stromal cells
and congested blood vessels. Different stages of the
follicles showed degenerated oocytes with pyknotic nuclei
and vacuolated cytoplasm. The surrounding granulosa cells
also appeared loosely arranged with vacuolated cytoplasm
and pyknotic nuclei. Separation between granulosa and
theca cell layers was observed.
Apoptosis of cells in testicular and ovarian tissues
exposed to noise was much more than control sections.
Positive stained immune cells in testes were scattered in the
testicular tissue. On the other hand, positive stained
apoptotic cells in the ovaries were primarily localized at
granulosa and theca cell layers. Only minority of positive
stained cells were dispersed elsewhere in the ovary.
Histomorphometric assessment of testes confirmed
the histological findings. The three parameters assessed in
the current study were significantly decreased in noise
groups of 20 days old rats and the 7 weeks old rats
compared to their controls. However, adult testicular tissue
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didn’t show significant differences. Regarding the ovary,
the measurement of the length showed significant
difference regarding the 20 days old rats and the 7 weeks
old rats, whereas in the adult group, it didn’t show
significant difference compared to the control groups. The
measurement of the width showed significant difference in
the prenatal group but it didn’t show significant differences
in the other two groups compared to their controls.