Evaluation of the effect of Nicotine on Palatogenesis in Mice Pre and Post natally

In this investigation fourty pregnant C57BL/6J mice were classified into two groups (I and II), each subdivided into two equal subgroups (Ia, Ib, IIa and IIb). Group I was the control group injected by sterile physiological saline daily from the 6ththrough the 15th gestation days. The Ia was sacrificed at 18th gestation days while; the Ib was sacrificed one day after delivery. Group II was the experimental group injected by 1.67 mg/kg N-Nitrosonornicotine (NNN) in saline of a final concentration 0.1% daily from the 6th - 15th gestation days. The IIa was sacrificed at 18th gestational days while the Ilb was sacrificed one day after delivery. The pregnant mice were sacrificed & their fetuses were measured and counted, decapitated, fixed in Bouin?s solution and prepared routinely for paraffin sectioning. For histological and morphometrical examination a routine H & E staining was performed, while for the immunohistochemical examination of Epidermal Growth Factor a serial sections were mounted on electrically charged slides. The cleft palate percentages of all groups were counted and statistically analyzed. Histological examination demonstrated that the palate of all control groups was normally developed, whereas the nicotine injected group demonstrated underdeveloped palatal shelves. The percentage of the cleft palate of nicotine injected group were 46.8% for IIa and 28.1% for IIb, also nicotine injected group showed complete closure but with persistence of epithelial seam in a percentage of 12.5% for IIa and 18.7% for IIb. Immunohistochemical examination demonstrated a moderate immune reaction to the EGF in the control group, while in the experimental group, the EGF expression in the palatal epithelium was negative and nearly absent in the mesenchymal tissue. Our investigation revealed that fetuses and offsprings were shorter and weighed less than those of the control group. Group II fetuses and offsprings had a smaller heads when compared to the control.