Notochord

Advanced 🏥 Healthcare / Medical

Definition

A flexible rod-like structure composed of cells and extracellular matrix that forms the main support axis in the embryos of all chordates and persists as the nucleus pulposus of intervertebral discs in vertebrates. It is the evolutionary precursor to the vertebral column.

Example Usage

During early development, the notochord signals surrounding tissues to form the vertebrae and spinal cord.

Origin

From Greek *noton* 'back' + *chorde* 'string' or 'cord.'

Fun Fact

Simple chordates like amphioxus retain their notochord throughout life as their primary skeletal support, while vertebrates largely replace it with bone.

Source: Definition backfill (hailey)

Related Terms