Developmental Anatomy

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

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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?