The copulation age of this group ranges from 7 days 21 hours to 8 days 21 hours. The seven somite embryo was chosen as the most advanced in this stage because with the formation of the eighth somite, the embryo begins to rotate around its longitudinal axis. In the human, the corresponding age group, as described by Streeter , extends from 1 to 12 somites. The number of somites is the most reliable criterion to determine developmental age.
KeywordsPrimitive Streak Dorsal Aorta Oral Plate Trophoblastic Giant Cell Uterine Lumen
Unable to display preview. Download preview PDF.