الفهرس 
REVIEW OF LITERATURE.Only 14 pages are availabe for public view
 |  | from | 173 |  |  |
| | | from | 173 | | |
Abstract
Prevention and control of damage to health, crops, and property by insects, fungi, and noxious weeds are the major goals of pesticide applications. As with use of any biologically active agent, pesticides have unwanted side-effects. Among these pesticides are the fungicides, the effect of which on pregnancy received little attention from the workers in the field of developmental toxicology. Therefore, the present investigation aimed to evaluate the reproductive and developmental toxicity of the conazole fungicide diniconazole during the organogenesis in pregnant mice. In order to achieve the aim of the present study the acute oral toxicity LD50 of diniconazole to virgin female mice was determined by the present author by the graphical method.
Healthy virgin, normal cyclic female SWR mice Mus musculus, aged 90–120 days old and weighing 20–30 g were used in the experiments. The animals were purchased from the animal house of the Theodor Bilharz research institute. Females were kept in separate cages bedded with paddy husk throughout the experimentation period. The mice were exposed to normal light, dark regimen at a room temperature 26 + 1°C. Virgin females were made pregnant by housing every three females with one male in separate cage overnight, checked next morning for presence of copulation plug.
Animals were orally dosed with diniconazole, in fungicide-treated groups or with corn oil in control one. All doses were administered as homogenous suspension in corn oil based on the daily recorded body weight of the individual animal. Actual administration (10 ml/kg) was based on body weight taken daily during dosing period.
In the present study, pregnant females were orally administered with 15.625mg/kg that equivalent to 1/8 LD0 (low dose) or 31.25mg/kg that equivalent to 1/4 LD0 (mid-dose) or 62.5 mg/kg that equivalent to 1/2 LD0 (high dose) diniconazole in the treated groups or with corn oil in the control group, at day 8 till day 17of gestation and sacrificed on 18th day. The number of Corpora Leutea and the implantation sites (live, dead fetuses and resorption sites) were recorded and the percent of preimplantation loss was estimated.
.
Virgin females weighing 25-30 g were divided into 4 groups and each group consisted of 8 animals. An oral dose was administered to each animal based on its body weight. Food and water were allowed to the experimental animals except for one hour before to one hour after dosing, to avoid vomiting. Toxic symptoms and mortality rates were recorded throughout 24 hours.
This study dealing with the effect of diniconazole on fetuses obtained on 18th day of gestation. In such case diniconazole was administered on day 8 of pregnancy till 17th day of gestation and sacrificed on day 18th of gestation. Three concentrations of diniconazole were also used in this section. During the gestation period, the maternal body weight was recorded daily. At 18th day of gestation, a caesarean section was made and the gravid uterus and its content were carefully examined as well as the maternal liver tissues were taken for histopathological and histochemical examination. The fetuses were exposed and examined for viability, external and skeletal malformations. Also, the number of corpora Leutea, pre and postimplantation loss, alive and dead fetuses and females with complete resorption were recorded.
The treated dams showed some clinical sings of diniconazole toxicity such as loss of appetite, ataxia, dizziness, nausea, dyspnea, diarrhea, abdominal cramp and general weakness. Moreover, the recorded results of the maternal toxicity were; a reduction of maternal body weight gain, corrected body weight gain and weight of gravid uterus in a dose dependent manner. Also, reduction in the relative weight of kidney and heart in all studied doses but an increase in absolute liver weight in low and mid doses were recorded
The hepatic tissues of dams showed marked histological alternations in dose dependent manure, these alternations include; a loss of hepatic architecture, reduction in the cytoplasmic material and nuclei were hypertrophic, irregular, open face or pyknotic. Also, inflammatory leucocytic infiltrations were observed around necrotic hepatocytes area with dilated and/or congested blood vessels and sinusoids. Concerning the PAS reaction, the hepatocytes of the liver of control dams and dams exposed to 15.63 mg/kg (low dose) were rich in glycogen where the cytoplasm gives strong reactivity. Moderate reactions were observed in most hepatocytes of female exposed mid doses where the reaction was less than the control liver. In contrast, severe reduction of glycogen was observed in the liver of females exposed highest dose. The observations were recorded in protein histochemistry by BPB method.
Diniconazole treatments during organogenesis were associated with developmental toxic impacts affecting pregnancy outcome. The toxic observations here includes a significant increase in resorption rate and the percentage of postimplantation loss per dam (resorped + dead), as well as increased percentage of dams with postimplantation loss at one or more sites. In addition, significant complete resorption of all implants was recorded in a large number of dams, complete miscarriage of all fetuses was recorded in significant number of dams, and consequently the percent of females producing live fetuses was significantly reduced. This leads to corresponding reduction in the number of live fetuses per dam.
Fetal growth retardation was reflected by a significant decrease in relative fetal body weight (in all doses), fetal length (in mid & high doses) and fetal weight per length ratio (only at high dose) but increase in placental weight in all studied treatments with regard to live fetuses.
It was interesting to note that diniconazole treatments were associated with external and skeletal malformations. External malformations affecting gross morphology of fetuses including general Edema, hematoma, micrognathia, kyphosis, microdactly, club foot, club hand and Kinky tail. Skeletal malformations in the sternum include dumb-bell sternebrae, malaligned sternebrae, asymmetric sternebrae, hemisternebrae, forked sternebrae, and absent sternebrae. Moreover, extra cervical rib (unilateral or bilateral) and extra lumber ribs (unilateral or bilateral) were clearly observed. This indicated that maternal exposure to diniconazole during organogenesis (GD8-GD17) might carry a selective degree of risk to developing fetuses, which implicated in a significant increase in the number of malformed fetuses and the percentage of dams with malformed fetuses.
Fetal skeletal analysis revealed a higher prevalence of anomalies in fetuses of diniconazole groups when compared with control group. The examination of the endoskeletal system of fetuses of pregnant mice that administered different doses of diniconazole during organogenesis period showed delayed ossification of the skeleton that clearly observed by reduced ossification centers; in the skull, cervical centra and caudal vertebrae, ribs, the fore and hind limbs mainly in the distal phalanges, metacarpals and metatarsals and sternebrae. Also, bones of ilium, ischium, pupis and clavicle displayed different degrees of ossification retardation. Among diniconazole treated groups a significant large number of dams produced a large number of individuals with retarded ossification of the skeleton.
In conclusion, oral administration of mid dose (31.25 mg/ kg) and high dose (62.5 mg/kg) of diniconazole during fetal periods produced reproductive and developmental toxicity. Diniconazole administration during organogenesis period was associated with fetotoxicity and lethality. Reproductive toxicity were reflect clearly in increased percent of dams with complete late resorption and abortion of all implants, reduced number of live fetuses and causes a fetal growth retardation as manifested by reduced fetal weight and length. Skeletal ossification retardation was clearly observed with increased incidence of external and skeletal malformations.
Results of the current study reflect clearly that the low dose of diniconazole (1/8 LD0) showed a slightly toxic effect on both