notochordal

The prechordal cells migrate to the midline to form the notochordal plate.

Sophineta differs from all kuehneosaurs and Marmoretta in having short notochordal vertebrae without transverse processes.

Persistence of notochordal cells within the vertebra may cause a pathologic condition- persistent notochordal canal.

The notochordal plate then serves as an anchor for the neural plate and pushes the two edges of the plate upwards while keeping the middle section anchored.

As it involutes, it converges along the mediolateral axis and extends along the future anterior-posterior axis of the notochordal and somitic mesoderm.

Expression of the brachyury gene has been identified as a definitive diagnostic marker of chordoma, a malignant tumor that arises from remnant notochordal cells lodged in the vertebrae.

Isolated notochordal remnants may escape their lineage-specific destination in the nucleus pulposus and instead attach to the outer surfaces of the vertebral bodies, from which notochordal cells largely regress.

The evidence for this is the location of the tumors (along the neuraxis), the similar immunohistochemical staining patterns, and the demonstration that notochordal cells are preferentially left behind in the clivus and sacrococcygeal regions when the remainder of the notochord regresses during fetal life.

Prior to neurulation, during the migration of epiblastic endoderm cells towards the hypoblastic endoderm, the notochordal process opens into an arch termed the notochordal plate and attaches overlying neuroepithelium of the neural plate.

Other differences are the presence of paired rather than confluent nares, the presence of weakly developed zygosphenoidal articulations on the vertebrae, the possession of notochordal rather than amphiplatyan vertebrae, and compressed keeled tooth tips rather than simple cones.