الفهرس 
THE OVARY IN RATSOnly 14 pages are availabe for public view
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Abstract
Many epidemiological studies correlated cigarette smoking with female infertility and other experimental studies explained this correlation due to the effect of cigarette smoking on the uterine tubal structure and motility or due to hormonal changes produced by the effect of smoking on the ovary. But few studies were done to reveal the effect of cigarette smoking on the structure of the ovary. So the aim of the present work was to study the effect of cigarette smoking and its main component, nicotine on the structure of the ovary of female albino rats.
For that reason, 10 pregnant albino rats were exposed to cigarette smoke and their female offsprings were divided into three groups which were also exposed to cigarette smoke for one, two and four months. Then the offsprings were sacrificed and their ovaries were examined by light and electron microscope. By the same manner, 10 pregnant albino rats and their female offsprings were injected with nicotine subcutaneously. Also 10 pregnant control albino rats and their female offsprings were injected with saline.
Examination of the histological transverse sections of the ovaries of the tested groups revealed that there was an ultimate statistical reduction in the total number of ovarian follicles in the female albino rats exposed to cigarette smoke. But this number was elevated in the female albino rats treated with nicotine. Also the number of primordial follicles was apparently reduced in female albino rats exposed to smoke or injected with nicotine. The ultimate reduction in the total number of ovarian follicles and the apparent reduction in the primordial follicles in female albino rats exposed to smoke might explain the early menopause associated with cigarette smoke inhalation that was reported by many epidemiological studies.
The total number of degenerated follicles was statistically increased in the ovaries of female albino rats exposed to smoke or injected with nicotine.
Destruction of the oocytes was evident in the histological transverse section of the ovaries of female albino rats exposed to smoke or injected with nicotine. The damaged oocytes appeared either collapsed with shrunken cytoplasm and pyknotic nuclei or as multiple dark masses surrounded by intact zona pellucida.
The increased number of degenerated follicles and the apparently increased number of damaged oocytes might explain the reduced pregnancy rate in female smokers undergoing IVF treatment.
The zona pellucida of some ovarian follicles were apparently thickened in the female albino rats exposed to smoke till the age of one and two months. The increased zona pellucida thickness might also have a negative influence on female fertility as mentioned by many authors.
In the ovaries of female albino rats treated with nicotine till the age of four month, damage to the zona pellucida was observed by light microscopy and wide spaces were also seen between the zona pellucida and the corona radiata cells by electron microscopy.
The granulosa cells of the ovarian follicles showed marked degeneration in all groups either exposed to smoke or treated with nicotine by light and electron microscopy. The destruction in the estrogen secreting cells, granulosa cells, might explain the reduced serum estrogen level in the female smokers.
The zone of theca interna showed a marked thickening in the ovaries of female albino rats exposed to smoke or injected with nicotine till the age of four months. This theca interna hyperplasia might be due to the ovarian congestion as mentioned by some authors.
Electron microscopic examination revealed damage to the theca cells and the granulosa lutein cells of the ovaries of female albino rats injected with nicotine till the age of two and four months which might explain the reduced serum progesterone level in female smokers.
The total number of corpora lutea was statistically reduced in the ovaries of female albino rats exposed to smoke or injected with nicotine. This reduction might indicate that cigarette smoking has a negative influence on ovulation as reported by many authors.
Some ovarian follicles, in the ovaries of female albino rats exposed to cigarette smoke till the age of four months, were ruptured with liberation of their oocytes into the interstitial tissue. This phenomenon was named by some authors IOR (intra-ovarian follicular rupture).
Moreover, in the ovaries of female albino rats injected with nicotine till the age of four months, some ovarian follicles were cystically dilated and this might support the assumption of some authors that cigarette smoking increased the rate of occurrence of ovarian cysts in female smokers.
The interstitial tissue mass was apparently increased on the expense of the follicular elements in the ovaries of female albino rats exposed to smoke till the age of four months. But the interstitial tissue, in the ovaries of female albino rats injected with nicotine till the age of four months, showed patches of fibrosis and thickening of the fibrous septa between the interstitial tissue cells.
Congestion of the blood vessels in the interstitial tissue and in the ovarian medulla was marked in the ovaries of female albino rats exposed to smoke till the age of two month and in the ovaries of female albino rats injected with nicotine till the age of two and four months.