Final answer:
The notochord is a critical embryonic structure found in all chordates, providing support and guiding development. It is only present during the embryonic stage in vertebrates and is replaced by the vertebral column.
Step-by-step explanation:
When discussing the notochord, we are referring to a flexible, rod-shaped support structure that is found in the embryonic stage of all chordates and persists in the adult stage of some chordate species. This structure is critical for the proper development of the vertebrate embryo, providing the necessary structural support for the embryonic body while also inducing the development of the neural tube.
The notochord is located between the nerve cord and the digestive tube, and, during the development of vertebrates, it is eventually replaced by the vertebral column (spine). One key stage of vertebrate development is the formation of the neural system, along with the vertebrate axis and the notochord, which come from the mesoderm layer in the embryo.
Misexpression of Sonic hedgehog (Shh), which is normally expressed in the chordomesoderm and notochord, might lead to a scenario where the animal would possess two notochords and potentially lack typical anatomical orientation such as dorsal-ventral or anterior-posterior side.
The given question is incomplete, The complete question is given below:
"How is Shh (Sonic Hedgehog) expressed in the context of embryonic development, specifically in which tissues such as chordomesoderm and notochord, and what role does its expression play in these tissues?"