<prompt> Embryonic period of development is:Up to 16 weeksUp to 12 weeksUp to 10 weeksUp to 8 weeks  <response>: Stages of Prenatal development 1. Germinal stage 0-2 weeks : Thegerminal stageis the period of gestation from feilization or conception, when the egg meets the sperm, to implantation of the embryo in the uterus 2 Embryonic Stage 3-8 weeks : Embryonic period extends from beginning of the third week to the end of eighth week of intrauterine life. 3 Fetal Stage 9 weeks to bih : Once cell differentiation is mostly complete, the embryo enters the next stage and becomes known as a fetus. The fetal period of prenatal development marks more impoant changes in the brain. This period of development begins during the ninth week and lasts until bih. 