الفهرس 
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Abstract
The present study was carried out to elucidate the teratogenic effect of some herbicides on rat’s fetuses during organogenesis. Atrazine, Metolachlor and Terbutryn were choosen for this work. Experiment was carried out on seven groups, each of 10 pregnant female rats. The first group was kept as control,
the second and third groups were administered atrazine orally in doses of 125 and 250 mg/kg. b.wt. respectively. The fourth and fifth groups were given orally metolachlor in doses of 139 and 278 mg/kg. b.wt. respectively. The sixth and seventh groups were administered terbutryn orally in doses of 125 and 250 mg/kg. b.wt. respectively. The tested herbicides were given daily from the 6~ to the 15th day of gestation, as this time of the period of organogenesis. Atrazine in doses of 125 and 250 mg/kg. b.wt. produced
decrease in the number of fetuses per mother, highly significant decrease in the number of viable fetuses, significant increase in the number of dead and resorbed fetuses per mother and significant decrease in body length
and weight of viable fetuses. Cleft palate in 50/ ,77.77%, thymus absence in 13.63%, 22.22%, thymus hypoplasia in 59.097,61.11%, pulmonary hypoplasia in 45.45j,61 .11% cardiac hyperplasia in 45.45/,liver enlargment in 27.27/155.55% and elargment of suprarenal gland in 81.817,83.33% of examined fetuses respectively were reported as visceral abnormalities. Skeletal examination revealed impaired ossification of skull in 30.76750%, absence of sternbrae in 53.847 ,75%, absence of caudal vertebra in 53.84/ 66.67%,
absence of digit’s bone of fore-and hind limb in 69.237, 91.67% and absence of metatarsal and metacarpal bones in53. 84/ , 58.33% of examined fetuses respectively. Histopathologica]. examination of fetus and internal organ of
mother following administration of atrazine revealed some changes in lung and spleen such as congestion of the peribronchial and perialveoalr capillaries, hyperplasia and metaplasia in epithelial lining of the bronchioles, thickening in the wall of blood vessels and narrowing of its lumen, and haemorrhagic areas in the spleen could be seen. Oral administration of 139 and 278 mg/kg. b.wt. of
metalachlor induced significant decrease in the number of fetuses per mother, highly significant decrease in the number of viable fetuses, significant increase in the number of dead and resorbed fetuses and highly significant decrease
in fetal weight and length. Visceral examination of living fetuses revealed microcephaly in 57.14% (in large dose), pulmonary hyperplasia in 29.63/ 52.38% enlargment of kidney in ‘IS.l5j 76.19%, dilatation of renal pelvis in 37.04/
61.90%, enlargment of suprarenal gland in 37.04/ 66.67% and coelomia in 14.817 61.90% of examined fetuses. Skeletal examination revealed impaired ossification of skull in 31.58/~46.67% absence of caudal vertebrae in 31.587,53.33%, abnormalities in ribs in 47.37/~60%, absence of digit’s bone of fore-and hind limb in 21.O5/~53.33% and absence of some metatarsal and metacarpal bones in 26.327,40% of examined fetuses. Histopathological examination of fetuses and
internal organ of mother showed congestion of the central viens, portal viens and portal blood vessels, lymphocytes and macrophages were observed around the central veins and replaced the destructed hepatic cells. Vacuolar and hydropic
degeneration could be observed. Edematous fiberous tissue proliferation among the degenerated muscle fibres with leucocytic infiltration could be seen in cardiac muscle. Some changes was seen in brain as neural degeneration in
cerebrum, congestion of cerebral blood vessels with focal area of gliosis. Cloudy swelling and vacuolar degeneration could be seen in the cortex of renal tubules, haemorrhagic areas with focal aggregation of inflammatory cells could be
seen in the medulla among the renal tubules and congestion
of glomeruli with periglomerular leucocytic cells infiltration mainly lymphocytes and macrophages. The placenta showed degeneration of trophoblast, necrosis of
trophoblast and lecucocytic infiltration with haemorrhage. Terbutryn in doses of 125 and 250 mg/kg. b.wt. induced significant decrease in the number of fetuses per mother and highly significant decrease in the number of viable fetuses, significant increase in the number of dead and resorbed fetuses and significant decrease in fetal length and weight. Thymus absence in 27.277,55.56%, thymus hypoplasia in 27.27/
33.33% liver enlargment in 45.457,0, and renal hypoplasia in 36.377~44.44% respectively of examined fetuses were recorded as visceral malformations. Skeletal examination revealedabnormalities in ribs in 36.36/~5O%~ absence of caudal
vertebrae in 45.457,60%, absence of digits of fore-and hind limb in 81 .si/, 90% and absence of some metacrpal and metatarsal bones in 72.72/, 80% of fetuses respectively. Histopathological examination of fetus and internal organs
of mother revealed liver and kidney lesions similar to those recorded in metolachlor, as well as congestion of the coronary blood vessels, Cardiac muscle showed vacuolar and hyaline degeneration with leucocytic infiltration. I-Iaemorrhagic area could be seen among fetal muscles. Some fetal bones as scapula humerus and femur were showed absence of calcification and ossification. Focal area of coagulative necrosis in epidermis was also recorded. The obtained fetal abnormalities as decrease in the number of the fetuses per mother might be attributed to the lack of oval production or of the basic cell constituent by
the mother. The decrease in the number of the viable fetuses as well as increase in the number of dead fetuses might be explained on the basis of incomplete formation of the placenta and degeneration of the trophoblast and decidual
cell which play an important role in the transmission of nutrient to the embryo. The increase in the number of resorbed fetuses might be attributed to the interference of
the tested herbicides with placental transmission of magenesium and amino acid leucin as deficiency of magnesium or leucin produced high incidence of fetal resorption. Disturbance in metabolism and the interference of the tested
herbicides to the placental transmission of some minerals as magnesium and zinc were the main causes of retardation in fetal growth. Deficiency of riboflavin amino acid produced cleft palate and deficiency of arginine amino acid caused
brain abnormalities such as reduction in size and weight. Abnromal morphogenesis of lung, heart and kidneys induced by tested herbicides might be attributed to the alteration of thyroid hormone status. The recorded skeletal malformation
might be attributed to the faulty in calcification of cartilages and impaired production of mucopolysaccharides due to deficency of manganese ions in the fetus.