1916. The first sign of future deciduous teeth as a thickening of oral ectoderm appears at about_____________? September 27, 2025 by Admin A. 25th day of Intra uterine life B. 34th day of Intra uterine life C. 56th day of Intra uterine life D. 20 wks of Intra uterine life ✅ The correct answer is option C. 56th day of Intra uterine life.