الفهرس 
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Abstract
AFB1 is known as a carcinogenic, teratogenic and mutagenic mycotoxin, the current study aims to demonstrate the adverse histological, developmental, morphological and biochemical effects of AFB1 on the developing chick embryo using doses that are extremely lower than the estimated LD50. Fertilized eggs of the chick Gallus domesticus were divided into five groups: control group, positive control group treated with AFB1 solvent (10% Ethanol) and three experimental groups treated with single doses of 5 ng, 10 ng or 20 ng of AFB1 extract. The histological investigations were recorded in nervous system and notochord of the early stages and liver, kidney and lung of the late stages using different histological stains. The mortality and hatchability rates were recorded. Specimens were morphologically examined at early and late stages of development. The hatched specimens were weighed, and morphometric measurements were carried out for some parameters: Crown-rump, head length, head circumference, head height, fore limb and the lengths of all parts of hind limb. Skeletal abnormalities were investigated in some other hatched specimens. Biochemical investigations were carried out at different embryonic stages. Current data showed some histological defects in the brain, eye, ear and notochord of the examined embryos of the early stages, as well as histopathological changes in liver, kidney and lung during the early and late stages of development. A decrease in hatchability rate in the treated groups compared to control was observed. Mortality rate was increased in treated groups compared to control. Weight and all morphometric parameters were significantly decreased in treated groups compared to control ones and insignificantly changed among the three treated groups. Different morphological malformations were observed in the early stages of the treated embryos such as brain and spinal cord deformations. The hatched embryos exhibited some morphological malformations such as growth retardation, brain deformation, invagination of the eyes, anophthalmia, beak deformities, wry and twisted neck, absence of feathers, abdominal hernia, limb deformities such as bud limbs or absence of limbs. Skeletal investigations showed poor ossification in the treated groups compared to control. Biochemical parameters such as GSH, Vitamin C., NO, SOD and LPO levels of the different stages of development showed some changes in the treated groups compared to control. The present study demonstrated that AFB1 causes histological, developmental, morphological and biochemical anomalies to the embryo. According to earlier literatures, AFB1 can cause severe congenital anomalies by altering DNA and protein synthesis depending on different factors such as dose, age, species and duration of exposure. The present study showed that the very low doses of AFB1 caused severe malformations to the chick embryo which is recommended to be considered in poultry industry and human concerns in food and feed.