الفهرس 
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Abstract
Arsenite, the more toxic inorganic form of arsenic, is widely distributed through drinking water and food. It is considered as a serious worldwide environmental health threat. It is known to affect the endocrine system and has showed adverse effects on the female reproductive system.
Human chorionic gonadotropin (hCG) is a glycoprotein hormone formed of alpha and beta subunits. It has been proved to play a protective role in several reproductive effects mediated by arsenic and other elements.
The aim of this study was to investigate the adverse effects of sodium arsenite on the endometrium of adult rat and to evaluate the possible role of hCG on these changes.
Thirty six adult female rats having regular estrous cycle phases and weighting 150-160 gm were used in this study.
The experimental animals were classified into three groups 12 animals each:
Group I (control group): The animals of this group were further subdivided into two subgroups (subgroup Ia and subgroup Ib) 6 animals each:
SUBGROUP (Ia): The animals were left without treatment.
SUBGROUP (Ib): The animals were subcutaneously injected with 0.1ml distilled water /100 gm body weight/day.
Group II (arsenic treated group): The animals received sodium arsenite orally at a dose of 0.4 ppm daily for 28 days.
Group III (Arsenic + hCG group): The animals were subcutaneously injected with hCG (pregnyl) at a dose of 1.0 IU for 28 days, together with the same previous dose of sodium arsenite.
Vaginal smears were taken two weeks before the experiment, between 9 and 10 am, to ensure regular estrous cycle and throughout the experiment to detect any change or irregularity in the cycle. The smears were stained by methylene blue stain.
At the end of the experiment all animals were sacrificed at diestrous phase. The uterine horns were dissected, cut into two halves and cleaned. Half of the specimens were fixed in 10 % formol saline and prepared for light microscopic examination using; Haematoxylin and eosin stain, Periodic acid-Schiff (PAS) (histochemical) technique and Masson’s Trichrome Stain.
The other half of the specimens were cut into small pieces, fixed in 1.5% gluteraldhyde and prepared for scanning electron microscope examination.
Moreover, morphometric measurements were done to detect; the mean height of the surface epithelium, the mean diameter and the mean number of the endometrial glands in all groups. The results were statistically analyzed.
Arsenite treatment altered the histomorphology of the endometrium and caused prolonged diestrous phase of the cycle. Light microscope examination revealed a significant reduction in the height of the surface epithelium. Some parts of the lining epithelium showed irregular shaped nuclei and apoptotic changes. The basement membrane was disrupted with no demarcation between the epithelial and the stromal tissues. The endometrial stroma was dense, disorganized and showed increase in collagen fibers content. Most cells of the stroma had spindle shaped nuclei. The endometrial glands showed a significant decrease in their number and diameter and many of them were atrophied with no secretory activity.
Scanning electron microscope revealed apparent decrease in the uterine horn diameter with narrow lumen. The surface epithelial cells became flattened with an apparent decrease in the number of cells with pinopodes. An apparent decrease in the number of pits of glands was also noticed.
A preservation of the endometrial histoarchitecture in group III animals was prominent. Normal estrous cycles were regained. Stratification, vacuolation and a significant increase in the height of the surface epithelium were also seen. Apparent increase in PAS positive granules in the surface epithelial and stromal cells was detected. The stroma became less dense and less fibrous compared with group II. The glands appeared normal and contained secretions.
Scanning electron microscope of this group revealed apparent increase in the uterine horn diameter with widening of its lumen compared with group II. Apparent Increase in the number of cells with pinopodes was prominent. Moreover, increase in the secretory activity with mucous patches and mucous bleb on the surface of epithelial cells was also detected.
In conclusion, our results indicated that arsenic, being an endocrine disruptor is a major threat to female reproductive health acting as a reproductive toxicant. Nearly all these changes in endometrium and in estrous cycle were disappeared with hCG coadministration.