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From our experiments we can conclude that doses of nicotine between 0.25 mg and 1.0 mg have adverse effects on chick embryo development. All chick embryos treated with 1.0 mg of nicotine were dead within 3 days. This outcome is in accordance with Gilani's observations that exposure to 1.0 mg of nicotine results in high instances of embryonic death.

When the treatment concentration of nicotine was decreased to 0.5 mg and 0.25 mg we still observed high instances of death. It is known that high amounts of nicotine reduces essential nutrients and oxygen supply to fetal tissues (Lambers and Clark 1996). This suggests that any dose of nicotine over 0.25 mg fatally interferes with embryonic development. Although, the treatment population was severely reduced due to casualties, two eggs survived until day 13 of development. Egg #8 exhibited significant underdevelopment compared to the controls. This can be attributed to the fact that nicotine inhibits the absorption of calcium, vitamin C, and essential minerals (Nash and Persaud 1989). Staining with Alcian green confirms this as large amounts of cartilage was observed in egg #8, whereas the control limbs exhibited evidence of further bone development.

Nicotine also has an affect on the circulatory system. Nicotine is a known stimulant that can lead to an increase in heart rate as our evidence suggests. It is also known to narrow the diameter of the blood vessels, thus slowing down the blood flow. Nicotine also increases the tendency of the blood to clot (Lambers and Clark 1996). The red skin color of egg #9 could be a result of these factors. We

©Cebra-Thomas, 2000

Last Modified: 5 May 2000

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