Write about notochord

Notochord forms the basis of the vertebrae and starts developing at the 16th day from the mesoderm cells of the embryo, afterward mature completely on the onset of the fourth week. It helps to design and develop the longitudinal axis of the embryo thereby, defining the correct position of the vertebral column. Eventually, the ectoderm starts growing into a neural plate along with the release of typical adhesion molecules. The molecules spread from the notochord into a neural plate and code neuroepithelial cells. Further, some neuroepithelial cells get signals from notochord and start elongation of the neural plate. The neural plate completely matures at the end of the third week of gestation. Later, most of the vertebral organs start developing from the neural plate. For example- In zebrafish, the cells in the notochord epithelium start the secretion of collagen cells (the complex of type 2 collagen cells that grow into notochord sheath. These cells later fix into the intravertebral spaces and elongate the notochord sheath. It is followed by the lateral bending of the lower longitudinal axis. The elongated cells enforce pressure on intravertebral ligaments to form amphicoelous (hourglass). This structure finally aids in the development stages and functions of the vertebrae cells by forming the vertebrae column. Got a question on this topic? The process of morphogenesis is functional for the formation of organs from premature cells and can be explained as- The notochord und...

All chordates start out as one cell, a zygote. Eventually we divide into multiple cells in a single layer called a blastula. Then in a process called gastriculation, the blastula develops into 3 embryonic layers, which are collectively called the embryonic germ layers. These are the ectoderm, or outer layer, the mesoderm, or the middle layer, and the endoderm, or inner layer. The product of gastriculation: a gastrula or 3-layered embryo. The notochord helps to provide rigid structure to the organism. In more complex organisms, such as humans, it eventually develops into a backbone. In less complex organisms, we see the retention of the notochord as a way to allow the flexibility that those organisms have. Think about watching a sturgeon jump out of the water or seeing a lamprey slither. They maintain their notochord and never develop a backbone as we do. In vertebrates, the vertebrae help to give structure, and protect our spinal nerve column. Without the vertebrae, we would not be able to stand straight up as we do. We owe much of this to the development of the notochord. The notochord is a flexible rod and primitive beginning to the backbone. It is found exclusively in the phylum Chordata, a group of animals defined by this characteristic and that we humans belong to. During embryonic development, chordates develop into three embryonic layers in a process called gastriculation. The middle layer called the mesoderm gives rise to the notochord from cells that become rigid....

A notochord is characteristic of developing chordates (which comprise amphioxus, tunicates and vertebrates), and, more arguably, is also found in some other animals. Although notochords have been well reviewed from a developmental genetic point of view, there has heretofore been no adequate survey of the dozen or so scenarios accounting for their evolutionary origin. Advances in molecular phylogenetics and developmental genetics have, on the one hand, failed to support many of these ideas (although, it is not impossible that some of these rejects may yet, at least in part, return to favor). On the other hand, current molecular approaches have actually stimulated the revival of two of the old proposals: first that the notochord is a novelty that arose in the chordates, and second that it is derived from a homologous structure, the axochord, that was present in annelid-like ancestors. In the long term, choosing whether the notochord is a chordate novelty or a legacy from an ancient annelid (or perhaps an evolutionary derivative from precursors yet to be proposed) will probably require descriptions of gene regulatory networks involved in the development of notochords and notochord-like structures in a wide spectrum of animals. For now, one-way forward will be studies of all aspects of the biology of enteropneust hemichordates, a group widely thought to be the key to understanding the evolutionary origin of the chordates. Chordate notochords in side views, cross sections (thro...

The notochord is the defining structure of the chordates, and has essential roles in vertebrate development. 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. In this review, I discuss the embryonic origin, signalling roles and ultimate fate of the notochord, with an emphasis on structural aspects of notochord biology. In vertebrates, the notochord arises from the dorsal organiser. Originally identified by Spemann and Mangold in amphibians, the dorsal organiser is a region of a vertebrate gastrulae that, when transplanted into prospective lateral or ventral regions of a host embryo, induces the formation of a second embryonic axis, while only contributing to notochord and prechordal mesendoderm ( The first major transition is from dorsal organiser to chordamesoderm. During early gastrula stages, the chordamesoderm, which is the direct antecedent of the notochord, becomes morphologically and molecularly distinct from other mesoderm. Cellular rearrangements involving the mediolateral intercalation and convergence of cells towards the dorsal midline, force the chordamesoderm into an elongated stack of cells. Genetic screens in zebrafish have identified two loci, floating head ( flh) and bozozok ( dharma – Zebrafish Information Network), as being essential for this transiti...

Citation styles Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA). Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list. Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites: Modern Language Association The Chicago Manual of Style American Psychological Association Notes: • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates. • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or...

Citation styles Encyclopedia.com gives you the ability to cite reference entries and articles according to common styles from the Modern Language Association (MLA), The Chicago Manual of Style, and the American Psychological Association (APA). Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list. Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites: Modern Language Association The Chicago Manual of Style American Psychological Association Notes: • Most online reference entries and articles do not have page numbers. Therefore, that information is unavailable for most Encyclopedia.com content. However, the date of retrieval is often important. Refer to each style’s convention regarding the best way to format page numbers and retrieval dates. • In addition to the MLA, Chicago, and APA styles, your school, university, publication, or institution may have its own requirements for citations. Therefore, be sure to refer to those guidelines when editing your bibliography or...

A notochord is characteristic of developing chordates (which comprise amphioxus, tunicates and vertebrates), and, more arguably, is also found in some other animals. Although notochords have been well reviewed from a developmental genetic point of view, there has heretofore been no adequate survey of the dozen or so scenarios accounting for their evolutionary origin. Advances in molecular phylogenetics and developmental genetics have, on the one hand, failed to support many of these ideas (although, it is not impossible that some of these rejects may yet, at least in part, return to favor). On the other hand, current molecular approaches have actually stimulated the revival of two of the old proposals: first that the notochord is a novelty that arose in the chordates, and second that it is derived from a homologous structure, the axochord, that was present in annelid-like ancestors. In the long term, choosing whether the notochord is a chordate novelty or a legacy from an ancient annelid (or perhaps an evolutionary derivative from precursors yet to be proposed) will probably require descriptions of gene regulatory networks involved in the development of notochords and notochord-like structures in a wide spectrum of animals. For now, one-way forward will be studies of all aspects of the biology of enteropneust hemichordates, a group widely thought to be the key to understanding the evolutionary origin of the chordates. Chordate notochords in side views, cross sections (thro...

Notochord forms the basis of the vertebrae and starts developing at the 16th day from the mesoderm cells of the embryo, afterward mature completely on the onset of the fourth week. It helps to design and develop the longitudinal axis of the embryo thereby, defining the correct position of the vertebral column. Eventually, the ectoderm starts growing into a neural plate along with the release of typical adhesion molecules. The molecules spread from the notochord into a neural plate and code neuroepithelial cells. Further, some neuroepithelial cells get signals from notochord and start elongation of the neural plate. The neural plate completely matures at the end of the third week of gestation. Later, most of the vertebral organs start developing from the neural plate. For example- In zebrafish, the cells in the notochord epithelium start the secretion of collagen cells (the complex of type 2 collagen cells that grow into notochord sheath. These cells later fix into the intravertebral spaces and elongate the notochord sheath. It is followed by the lateral bending of the lower longitudinal axis. The elongated cells enforce pressure on intravertebral ligaments to form amphicoelous (hourglass). This structure finally aids in the development stages and functions of the vertebrae cells by forming the vertebrae column. Got a question on this topic? The process of morphogenesis is functional for the formation of organs from premature cells and can be explained as- The notochord und...

All chordates start out as one cell, a zygote. Eventually we divide into multiple cells in a single layer called a blastula. Then in a process called gastriculation, the blastula develops into 3 embryonic layers, which are collectively called the embryonic germ layers. These are the ectoderm, or outer layer, the mesoderm, or the middle layer, and the endoderm, or inner layer. The product of gastriculation: a gastrula or 3-layered embryo. The notochord helps to provide rigid structure to the organism. In more complex organisms, such as humans, it eventually develops into a backbone. In less complex organisms, we see the retention of the notochord as a way to allow the flexibility that those organisms have. Think about watching a sturgeon jump out of the water or seeing a lamprey slither. They maintain their notochord and never develop a backbone as we do. In vertebrates, the vertebrae help to give structure, and protect our spinal nerve column. Without the vertebrae, we would not be able to stand straight up as we do. We owe much of this to the development of the notochord. The notochord is a flexible rod and primitive beginning to the backbone. It is found exclusively in the phylum Chordata, a group of animals defined by this characteristic and that we humans belong to. During embryonic development, chordates develop into three embryonic layers in a process called gastriculation. The middle layer called the mesoderm gives rise to the notochord from cells that become rigid....

The notochord is the defining structure of the chordates, and has essential roles in vertebrate development. 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. In this review, I discuss the embryonic origin, signalling roles and ultimate fate of the notochord, with an emphasis on structural aspects of notochord biology. In vertebrates, the notochord arises from the dorsal organiser. Originally identified by Spemann and Mangold in amphibians, the dorsal organiser is a region of a vertebrate gastrulae that, when transplanted into prospective lateral or ventral regions of a host embryo, induces the formation of a second embryonic axis, while only contributing to notochord and prechordal mesendoderm ( The first major transition is from dorsal organiser to chordamesoderm. During early gastrula stages, the chordamesoderm, which is the direct antecedent of the notochord, becomes morphologically and molecularly distinct from other mesoderm. Cellular rearrangements involving the mediolateral intercalation and convergence of cells towards the dorsal midline, force the chordamesoderm into an elongated stack of cells. Genetic screens in zebrafish have identified two loci, floating head ( flh) and bozozok ( dharma – Zebrafish Information Network), as being essential for this transiti...