GENERAL HISTOLOGY

Detailed explanation-1: -A notochord is a rod-like structure that helps as a very important function and is attached to their muscles. In humans who are vertebrate chordates, the notochord is replaced with a spinal cord. This difference is the main feature that separates invertebrate chordates from vertebrates chordates.

Detailed explanation-2: -It serves as a source of midline signals that pattern surrounding tissues and as a major skeletal element of the developing embryo. Genetic and embryological studies over the past decade have informed us about the development and function of the notochord.

Detailed explanation-3: -Living species of chordates are classified into three major subphyla: Vertebrata, Urochordata, and Cephalochordata. Vertebrates are all chordates that have a backbone. The other two subphyla are invertebrate chordates that lack a backbone. Members of the subphylum Urochordata are tunicates (also called sea squirts).

Detailed explanation-4: -notochord, flexible rodlike structure of mesodermal cells that is the principal longitudinal structural element of chordates and of the early embryo of vertebrates, in both of which it plays an organizational role in nervous system development.