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Determining the effects of nicotine on bone and cartilage development in chicks (Gallus gallus) Sean Anderson Biology 024: Embryology Swarthmore College, Swarthmore, PA Spring 2004 Objective The purpose of this experiment is to determine how the development of bone and cartilage in a chick are affected by treating the embryo with nicotine at early stages of development. Introduction Maternal smoking during pregnancy has long been recognized as a hazard, increasing the incidence of premature delivery, spontaneous abortion, low birth weight, and neonatal mortality. There is also an increase in the occurrence of lower respiratory illnesses, which suggests that smoking can effect lung development of the fetus during pregnancy. Nicotine, which is able to cross the placental barrier, may be the primary cause of many of the effects of maternal smoking during pregnancy. In experimental studies, maternal nicotine exposure elicits the same effect on neonates as direct smoking by the mother (Pierce and Nugyen, 2001). Many studies have also found that, for example, women who smoke during pregnancy increased the risk that their children would develop asthma, and this is especially true in families with a history of asthma. Nicotine may adversely affect lung function by increasing airway resistance, diminishing airway conductance, decreasing peak tidal expiratory flow, and increasing respiratory time (Maternal Smoking During Pregnancy). Nicotine, the chief alkaloid in tobacco, is known to have other adverse effects on body development also. Smoking during pregnancy is also known to affect the child’s intelligence in later years. One study offered evidence that maternal cigarette smoking during pregnancy poses a unique risk for neurodevelopmental impairment among children, which is manifested as early as the first four year where the child’s intellectual functioning is severely impaired (Olds et al. 1994). Nicotine exposure is also known to cause growth restriction, premature rupture of membranes, and an increase in heart rate. Nicotine is impairs the absorption of calcium, vitamin C, and other vitamins and minerals required by a developing fetus. Researchers have demonstrated similar effects similar to those in humans as a result of maternal nicotine exposure in rats, including reductions in ossification in the femur, forelimb, nasal bone, ribs, and the skull and face (Elliott and Unger, 2000; Paulson et al. 1994). The retardation of bone development may be due to and an inhibition of calcium absorption by nicotine. This suggests that nicotine causes abnormalities in embryonic bone development. This experiment is intended to examine the effects of embryonic exposure to nicotine on bone and cartilage formation in chicks.