- The Nemertean Theory
In 1883, Hubrecht made the next attempt to turn invertebrates into vertebrates. He chose nemertean-like ancestors (not requiring dorsoventral inversion) to begin his scenari… See more
EvoDevoThe Original Enteropneust ScenarioAlthough earlier biologists had vaguely suggested that enteropneust hemichordates might be precursors of the vertebrates, Bateson, in 1886, was the first to present … See more
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- The notochord is a key evolutionary structure in chordates1. It originated more than 560 million years ago from a common ancestor shared with nonchordate deuterostomes1. In vertebrates, the notochord develops during gastrulation from cells that migrate anteriorly in the midline between the hypoblast and the epiblast2. It later becomes part of the vertebral column2. There are two main hypotheses for the origin of the notochord: the de novo theory and the axochord theory3.
Learn more:✕This summary was generated using AI based on multiple online sources. To view the original source information, use the "Learn more" links.They probably originated more than 560 million years ago from a common ancestor shared with nonchordate deuterostomes (echinoderms and hemichordates), and the occurrence of a novel fishlike (tadpole-type) larva was a key evolutionary event leading to the evolution of chordates.neupsykey.com/evolutionary-origin-of-the-notochord/In later vertebrate development, it becomes part of the vertebral column. The notochord derives during gastrulation (infolding of the blastula, or early embryo) from cells that migrate anteriorly in the midline between the hypoblast and the epiblast (inner and outer layers of the blastula).www.britannica.com/science/notochordTwo main hypotheses for the origin of the notochord were proposed, the de novo theory and the axochord theory. The former states that notochord has developed de novo from the mid-dorsal archenteron of a chordate ancestor with simple morphology and no central nervous system nor notochord homolog.www.mdpi.com/1424-2818/13/10/462 The development of the human notochord - PMC
The development of the human notochord has three distinct phases, leading to the definitive notochord, also dubbed the notochord proper or notochord senso stricto. This structure develops in three phases between Carnegie stage 8 …
Notochord - Wikipedia
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 …
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Did the notochord evolve from an ancient axial muscle? The …
The origin of the notochord is one of the key remaining mysteries of our evolutionary ancestry. Here, we present a multi‐level comparison of the chordate notochord to the axochord, a paired …
(PDF) Evolution of the notochord - ResearchGate
Oct 5, 2015 · The transition from notochord to vertebral column is a crucial milestone in chordate evolution and in prenatal development of all vertebrates.
Development of the annelid axochord: Insights into …
Sep 12, 2014 · We identify a population of mesodermal cells in a developing invertebrate, the marine annelid Platynereis dumerilii, that converges and extends toward the midline and expresses a notochord-specific combination of genes.
Evolution of the notochord - PubMed
Oct 5, 2015 · 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 …
Origin of the Chordate Notochord - MDPI
Sep 25, 2021 · During the late 20th century, the development of molecular and genetic tools in biology brought about a revival of studies on the evolutionary path of notochord development. Two main hypotheses for the origin of the …
Development and involution of the notochord in the human spine.
The availability of a collection of fetal and embryonic spines made possible a review of the involution of the notochord. Results of this histological, histochemical and …
Animal Evolution: Stiff or Squishy Notochord Origins?
Dec 1, 2014 · The notochord is considered an evolutionary novelty and one of the defining characters of chordates. A new study of an annelid challenges this view and proposes an earlier evolutionary origin in the most recent common …
The Notochord | Development, Evolution and contributions to the …
May 9, 2022 · Recent studies on zebrafish and medaka embryos have uncovered the molecular mechanisms of a somite-independent notochord-driven segmentation process that establishes …
How was the notochord born? - PubMed
In this review, we discuss the molecular mechanisms involved in the formation of the notochord over the course of chordate evolution with a special emphasis on a member of T-box gene …
Animal Evolution: Stiff or Squishy Notochord Origins?
Dec 1, 2014 · The notochord is considered an evolutionary novelty and one of the defining characters of chordates. A new study of an annelid challenges this view and proposes an …
Development of the annelid axochord: insights into notochord …
Sep 12, 2014 · The origin of chordates has been debated for more than a century, with one key issue being the emergence of the notochord. In vertebrates, the notochord develops by …
Ancestral state reconstruction suggests that contractile mesodermal midline cells existed in bilaterian ancestors. We propose that these cells, via vacuolization and stiffening, gave rise to …
Evolution of the notochord - PMC - National Center for …
Oct 5, 2015 · In 1905, Lameere published a scheme for notochord evolution that started with cnidarians—specifically with a creature resembling a sea anemone. A modern sea anemone …
How was the notochord born? - Satoh - 2012 - Evolution & ...
In this review, we discuss the molecular mechanisms involved in the formation of the notochord over the course of chordate evolution with a special emphasis on a member of T-box gene …
(PDF) Origin of the Chordate Notochord - ResearchGate
Sep 25, 2021 · During the late 20th century, the development of molecular and genetic tools in biology brought about a revival of studies on the evolutionary path of notochord development. …
How was the notochord born? - Satoh - 2012 - Evolution & ...
Jan 27, 2012 · In this review, we discuss the molecular mechanisms involved in the formation of the notochord over the course of chordate evolution with a special emphasis on a member of …
Scientists Have Grown a Human Spine In a Lab - Popular …
19 hours ago · “The notochord acts like a GPS for the developing embryo, helping to establish the body’s main axis and guiding the formation of the spine and nervous system,” James Briscoe, …
