notochord
The biology student carefully examines the notochord in the preserved embryo specimen.
Noun: A flexible, rod-shaped structure that serves as the primary supportive axis of the body in certain animals. It is found in the embryos of all vertebrates and persists as a defining feature in the adults of the most primitive chordates (like lancelets and tunicates) and some primitive vertebrates (like hagfish and lampreys).
The term is used in biological and zoological contexts to describe a key anatomical feature that defines the phylum Chordata. It is a fundamental concept in developmental biology and evolutionary studies.
- In embryology, the notochord is one of the first structures to form and plays a crucial role in organizing the development of the nervous system.
- The lancelet retains its notochord throughout its life, extending from head to tail.
- In higher vertebrates, the notochord is eventually replaced by the vertebral column, or spine.
- Notochordal: The adjective form, meaning "of or relating to the notochord."
- Example: The notochordal tissue secretes signals that induce the formation of neural tissue.
- Chordate (noun): Any animal of the phylum Chordata, characterized by having a notochord at some stage of its life cycle.
- Vertebrate (noun): An animal with a backbone or spinal column, which develops from and replaces the embryonic notochord.
- Primitive spine
- Axial rod
The word "notochord" has a single, specific meaning in biology. It does not have other common definitions.
This is a technical, scientific term. It is not used in idioms or phrasal verbs.
The biology student carefully examines the notochord in the preserved embryo specimen.
- a flexible rodlike structure that forms the supporting axis of the body in the lowest chordates and lowest vertebrates and in embryos of higher vertebrates