الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Trichloroethylene (TCE) is a chlorinated hydrocarbon, not naturally found in the environment (man-made), it is a colourless non-flammable liquid with a sweet odour. TCE is produced in the petrochemical industry and has many uses, such as in dry cleaning operations, paint and printing ink removal, fumigation of rodents, manufacturing fluorocarbons, and as an anaesthetic agent. Trichloroethylene is readily absorbed following both oral and inhalation exposures. It is also absorbed from the gastrointestinal tract into the systemic circulation. Once absorbed, TCE diffuses readily across biological membranes and is widely distributed to tissues and organs via the circulatory system, such as lungs, liver, kidneys and central nervous system. The present study was concerned with the effect of TCE on pregnant mice and their embryos. In addition, other parameters were also studied. The non-pregnant females were divided into three groups (each contains 30 virgin females) and treated as follows:- - The control group (C) was treated daily with corn oil only for 21 days before mating. - The females of group one (G1) were treated daily with low dose of TCE (1/100 of LD50, 24 mg/kg b.wt.) for 21 days before mating. - The females of group two (G2) were treated daily with high dose of TCE (1/10 of LD50, 240 mg/kg b.wt.) for 21 days before mating. All groups were orally treated by stomach tube with low and high doses of TCE (24 mg/kg b.w. and 240 mg/kg b.wt.). The treated females of each group allowed to mate with normal active male, treating of pregnant females with low and high doses of TCE was continued until days 5, 7 and 17 of gestation. Some of the pregnant females were sacrificed on days 6th and 8th of gestation. Other pregnant females were sacrificed on day 18th of gestation for collection and examination of foetuses. Morphologically, TCE treatment caused the following effects: The females of G2 showed loss of appetite and marked decrease in body weights. In contrast with group (C), the females of G1 showed little decrease in body weights. The percentage of survival was decreased in members of G2 than that of G1 during experimentation. The females of G2 showed marked decrease in successful copulation with normal males, comparable with the control group. The percentage of decrease of successful copulation was proportional with the concentration of the used dose. The percentage of foetal mortality, resorbed foetuses and stillbirths was generally increased in all the treated groups compared with the control. The growth retardation of foetuses on day 18 of gestation maternaly treated with TCE was indicated by the reduction in foetal body weight and length. TCE caused malformations of foetuses that examined on day 18 of gestation. These malformations included kyphotic body, uni-& bilateral malformation of both fore -& hind limbs, kinky tail and presence of superficial haematomas in the head, neck and trunk regions. These abnormalities were observed at higher rates in animals of G2. Osteological studies of foetuses on day 18 of gestation maternally treated with TCE showed the following alterations: Various kinds of skeletal defects in the skull elements of foetuses of G1 and G2 in the skull elements were demonstrated such as nasals, parietals, interparietals, supraoccipital, basioccipital, tympanic ring, and exoccipitals. These structures exhibited moderate to high retardation in ossification. Also, the premaxillae, maxillae, and zygomatic arches were affected. Foetuses of G2 examined on day 18 of gestation showed severe retardation in ossification of some skull elements such as nasals, parietals and supraoccipitals. In addition, complete lacking of ossification of interparietals, basioccipital, tympanic ring, and exoccipitals were observed. Furthermore, lack of ossification was clearly evidented in the lower jaw. Foetuses of G2 exhibited much decrease in ossification of most vertebral elements. The sternal components and ribs of foetuses belonging to G1 showed, more or less, normal appearance. However, most of the examined foetuses of G2 showed moderate or non ossified sternebrae and ribs. The effects of TCE on both girdles and limbs were proportional with the used doses. Foetuses of G1 showed moderate reduction in ossification. At the same time, foetuses of G2 showed pronounced reduction in the degree of ossification and a decrease in the length of the fore and hind limbs components compared with the control group. Examination of early embryos at 6th and 8th days of gestation maternally treated with TCE showed the following alterations: Few embryos of G1 at 6th day of gestation (132 hr p.c.) showed very little variations from the control which may not affect their normal development. However, some embryos showed signs of deformation such as lacking of the ectoplacental cone. However, some embryos of G2 showed signs of degeneration or destruction. Embryos at 8th day of gestation (180 hr p.c.) showed some abnormalities in the ectoplacental cone, ectoplacental cavity, as well as the exocoelomic cavity. The amniotic cavity was hard to detect in some embryos and be reduced in some others. The endoderm is not differentiated in some specimens into distal and proximal endoderm. The degenerated decidua showed vacuolated cells with pyknotic nuclei. Haemorrhage was also observed in different areas of the decidua around the abnormal developing embryos. In addition, some embryos of G2 showed clear signs of growth retardation than that of G1. The liver and kidneys of the pregnant females and their foetuses on day 18 of gestation previously treated with TCE showed pronounced histopathological alteration as follows: Numerous hepatic cells showed advanced degrees of hydropic degeneration, necrosis, and numerous focal areas appeared with lymphatic infiltration. Most nuclei exhibited noticeable signs of pyknosis, karyorrhexis, and almost complete karyolysis. The liver of animals of G2 showed more pronounced and wider spread distructive areas than that of G1. Examination of kidneys of pregnant females treated with low dose of TCE (G1) and their foetuses at 18th day of gestation showed normal renal tissue with no signs of pathological alterations. However, few renal tubules showed some degenerated cells. The histopathological changes observed in the kidneys of animals of G2 are manifested by massive peritubular inflammatory cellular infiltration, increased sloughing of the tubules and degeneration of their lining epithelial cells associated with marked distension of their tubular lumina. The glomeruli showed marked increase of cellularity, some of them were collapsed. Periglomerular renal cells infiltration was also observed. In sum, the present study revealed that oral administration of TCE to pregnant female mice caused signs of maternal toxicity, embryolethality and foetal development retardation; so it is considered as a teratogenic agent. The present author recomended that precautions must be taken on using this substance espacially pregnant women.