Formation of notochord and nerve cord in embryo with their function

by • 07/03/2012 • New Pattern Biology NotesComments (0)545


Formation of notochord:

Mesodermal cells are the mid dorsal axis form a dorsal rod like structure is called notochord. It acts as a supporting organ of the embryo.

Formation of nerve cord:

The ectodermal cells at the mid-dorsal axis just above the notochord sink inward to form a neural tube is called nerve cord. The nervous system develops from nerve Cord. At this point, the embryo is called neurula.

Tad-pole Larva:

The neurula rapidly enlongates to form a tail. Different organs and systems gradually develop from the three germinal layers. The embryo now hatches and is termed as Tadpole larva. It has a fish-like body having external gills which are soon replace by internal gills. It swims in water and feed upon aquatic vegetations.

Metamorphosis:

After an active free swimming phase, the tadpole larva passes through a series of rapid changes that transform it into the tailless adult frog.

“The process involving series of changes that transform tad-pole larva into adult is known as metamorphosis.

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