GENERAL HISTOLOGY

Detailed explanation-1: -1: Defining characteristics of chordates: In chordates, four common features appear at some point during development: a notochord, a dorsal hollow nerve cord, pharyngeal slits, and a post-anal tail.

Detailed explanation-2: -All chordates have a notochord at some stage in their lives, but in some (such as tunicates) the notochord is lost in the adult, whereas in others (such as the vertebrates) the notochord is present in the embryo, but in later stages is largely replaced and surrounded by the vertebrae, or backbones.

Detailed explanation-3: -Chordates are animals that have a notochord, post-anal tail, dorsal hollow nerve cord, and pharyngeal slits.

Detailed explanation-4: -All chordates have a post-anal tail. A post-anal tail is an extension of the body that runs past the anal opening. In some species, like humans, this feature is only present during the embryonic stage. The chordata phylum is divided into three groups or subphylums: lancelets, tunicats, and vertebrates.

Detailed explanation-5: -All chordates possess, at some point during their larval or adult stages, five synapomorphies, or primary physical characteristics, that distinguish them from all the other taxa. These five synapomorphies include a notochord, dorsal hollow nerve cord, endostyle or thyroid, pharyngeal slits, and a post-anal tail.