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Red: notochord; Magenta: axochord; Green: nerve chord; Blue: epidermis; Yellow: mesoderm. The notochord is an elastic, rod-like structure found in chordates. In chordate vertebrates the notochord is an embryonic structure that disintegrates, as the vertebrae develop, to become the nucleus pulposus in the intervertebral discs of the vertebral ...
The number of vertebrae in a region can vary but overall the number remains the same. In a human spinal column, there are normally 33 vertebrae. [3] The upper 24 pre-sacral vertebrae are articulating and separated from each other by intervertebral discs, and the lower nine are fused in adults, five in the sacrum and four in the coccyx, or tailbone.
A typical vertebra has a body (vertebral body), also known as the centrumwhich consists of a large anterior middle portion, and a posterior vertebral arch, [2] also called a neural arch. [3] The body is composed of cancellous bone , which is the spongy type of osseous tissue , whose microanatomy has been specifically studied within the pedicle ...
Branchiostoma lanceolatum has an elongated body, flattened laterally and pointed at both ends. A stiffening rod of tightly packed cells, the notochord, extends the whole length of the body. Unlike vertebrates, the notochord persists in the adult, in the form of a simple dorsal neural tube slightly thickened in the anterior part (the cerebral ...
The vertebral column, also known as the spinal column, spine or backbone, is the core part of the axial skeleton in vertebrate animals.The vertebral column is the defining and eponymous characteristic of the vertebrate endoskeleton, where the notochord (an elastic collagen-wrapped glycoprotein rod) found in all chordates has been replaced by a segmented series of mineralized irregular bones ...
The circulatory system carries food throughout their body, but does not have red blood cells or hemoglobin for transporting oxygen. Lancelet genomes hold clues about the early evolution of vertebrates: by comparing genes from lancelets with the same genes in vertebrates, changes in gene expression, function and number as vertebrates evolved can ...
The notochord plays an integral role in the development of the neural tube. 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.
Sectional organization of spinal cord. The spinal cord is the main pathway for information connecting the brain and peripheral nervous system. [3] [4] Much shorter than its protecting spinal column, the human spinal cord originates in the brainstem, passes through the foramen magnum, and continues through to the conus medullaris near the second lumbar vertebra before terminating in a fibrous ...