Stage 9: Lab Manual - Horizon 9
- 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.
Stage 9: Animation
Developmental Stages in Human Embryos by Ronan O'Rahilly and Fabiola Müller.
Published by Carnegie Institution of Washington, Publication 637. 1987.
Stage 9 (PDF 570 KB)
QUESTION: Where do the lateral limiting sulci appear?