Question

1. List the sequence of developmental stages from primitive groove to spinal cord. ( embryology lab)

Answer 1

Notochord is the defining structure of the chordate and as major skeletal element of the developing embryo.It derives during gasrulation.

Development from notochord to spinalchord is described below:

• Proliferation of cells from primitive pit forms a cord of cells in median plate till prochordal plate.
• Canalization of the process forms notochordal canal.
• Fusion between chord of the canal and endoderm
• Temporary communication between amniotic cavity and yolk sack due to degeneration of floor of notochordal canal and underlying endoderm.
• Regeneration of endoderm only.persistent roof of notochordal canal becomes folded upon itself to form defentive notochord.
• Neural tube arises from the ectoderm overlying the notochord
• Development of spinal chord.