• Length 1.5 - 2.5 mm
• 1-3 somites present
• The rostral and caudal ends of the embryo begin to be elevated "above" (dorsal to) the level of the umbilical vesicle.
• Lateral limiting sulci appear at first rostrally and then in the caudal part of the embryo.
• Presence of the detached fore-gut is a necessary prerequisite for head detachment.
• Ovulation age: 19 - 21 days

Question: Where do the lateral limiting sulci appear?

Developmental Stages in Human Embryos by Ronan O'Rahilly and Fabiola Müller.  Published by Carnegie Institution of Washington, Publication 637. 1987. Stage 9 (PDF)

Stage 8

Stage 10