Vertebral column which the bony endoskeleton is derived from? (a)Dorso-ventral nerve cord (b)Ventral nerve cord (c)Outgrowth of cranium (d)Notochord
Option D The vertebral column is derived from notochord or Chorda dorsalis. Animals having notochord either in their early developmental stage or throughout life are called chordates. The notochord is a rod-like supportive structure situated immediately below the nerve cord and above the alimentary canal. The notochord is made up of special vacuolated cells that are filled with semi-fluid substance. The cells are turgid, which give the notochord its stiff nature. The notochord cells are covered by the notochordal sheath. Notochord acts as the primitive internal skeleton and a rigid axis. It also allows the movement of the body. The notochord present in the embryonic stage is replaced partially or fully by the vertebral column in the adult.
