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In vertebrates, landmarks of embryonic neural development include the birth and differentiation of neurons from stem cell precursors, the migration of immature neurons from their birthplaces in the embryo to their final positions, outgrowth of axons from neurons and guidance of the motile growth cone through the embryo towards postsynaptic partners, the generation of synapses between these axons and their postsynaptic partners, and finally the lifelong changes in synapses which are thought to underlie learning and memory.
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vertebrates and embryonic
In response to Haeckel ’ s evolutionary claim that all vertebrates are essentially identical in the first month of embryonic life as proof of common descent, His responds by insisting that a more skilled observer would recognize even sooner that early embryos can be distinguished.
In vertebrates, a special population of embryonic cells called the neural crest has been proposed as a " fourth germ layer ", and is thought to have been an important novelty in the evolution of head structures.
Coelacanths also retain a notochord, a hollow, pressurized tube which is replaced by the vertebral column early in embryonic development in most other vertebrates.
The non-visual functions of vitamin A are essential in the immunological function, reproduction and embryonic development of vertebrates as evidenced by the impaired growth, susceptibility to infection and birth defects observed in populations receiving suboptimal vitamin A in their diet.
Haeckel's concept explained, for example, why humans, and indeed all vertebrates, have gill slits and tails early in embryonic development.
Evidence to support a " new " vertebrate head comes from the observation that most important features of the head are derived from neural crest cells, embryonic cells found only in vertebrates.
Although embryogenesis occurs in both animal and plant development, this article addresses the common features among different animals, with some emphasis on the embryonic development of vertebrates and mammals.
In zebrafish, lack of caveolins leads to embryonic lethality, suggesting that higher vertebrates ( as exemplified by mice ) have developed compensation or redundancy for the functions of caveolins.
vertebrates and neural
Versions of FOXP2 exist in similar forms in distantly related vertebrates ; functional studies of the gene in mice and in songbirds indicate that it is important for modulating plasticity of neural circuits.
Experiments on theoretical issues in conditioning have mostly been done on vertebrates, especially rats and pigeons, but conditioning has also been studied in invertebrates, and very important data on the neural basis of conditioning has come from experiments on the sea slug, Aplysia.
The term chromatophore was adopted ( following Sangiovanni's chromoforo ) as the name for pigment bearing cells derived from the neural crest of cold-blooded vertebrates and cephalopods.
In vertebrates, the ectoderm has three parts: external ectoderm ( also known as surface ectoderm ), the neural crest, and neural tube.
Hagfishes lack a true vertebral column, and are therefore not properly considered vertebrates, but a few tiny neural arches are present in the tail.
However, all vertebrates develop a kink in the neural tube that is still detectable in the adult central nervous system, known as the cephalic flexure.
In vertebrates, Shh signaling in the ventral portion of the neural tube is most notably responsible for the induction of floor plate cells and motor neurons.
All vertebrates have a forebrain whose upper surface is covered with a layer of neural tissue called the pallium, but in all except mammals the pallium has a relatively simple three-layered cell structure.
The neural crest is responsible for a large part of early development in vertebrates.
Studies on thermoregulation of ruin lizards and mice have informed some connections between the neural and genetic components of both vertebrates when experiencing induced hypothermic conditions.
The anteroposterior regionalization of the neural tube in ascidians is comparable to that in vertebrates.
In vertebrates, dorso-ventral patterning of the developing neural tube is achieved by the counteracting activities of morphogenetic signaling gradients set up by Sonic Hedgehog ( Shh ) in the ventral floor plate and notochord, and the canonical Wnt / β-catenin pathway acting in the roof plate, the dorsal most region of the neural tube.
An interesting trait is that its three-section body plan is no longer present in the vertebrates, except for the anatomy of the frontal neural tube, later developed into a brain which is divided into three main parts.
Putative neural crest gene-regulatory network functioning at the neural plate border in vertebrates.
Several structures that distinguish the vertebrates from other chordates are formed from the derivatives of neural crest cells.
In vertebrates, an odontoblast is a biological cell of neural crest origin that is part of the outer surface of the dental pulp, and whose biological function is dentinogenesis, which is the creation of dentin, the substance under the tooth enamel.
Although anatomical details of CPGs are specifically known in only a few cases, they have been shown to originate from the spinal cords of various vertebrates and to depend on relatively small and autonomous neural networks ( rather than the entire nervous system ) to generate rhythmic patterns.
vertebrates and development
Haeckel proposes that all classes of vertebrates pass through an evolutionarily conserved “ phylotypic ” stage of development, a period of reduced phenotypic diversity among higher embryos.
Nevertheless, it now appears that just as evolution tends to create new genes from parts of old genes ( molecular economy ), evo-devo demonstrates that evolution alters developmental processes to create new and novel structures from the old gene networks ( such as bone structures of the jaw deviating to the ossicles of the middle ear ) or will conserve ( molecular economy ) a similar program in a host of organisms such as eye development genes in molluscs, insects, and vertebrates.
In summary, " more than 300 separate actions of PRL have been reported in various vertebrates, including effects on water and salt balance, growth and development, endocrinology and metabolism, brain and behavior, reproduction, and immune regulation and protection ".
Pitx1 is a homeobox gene involved in posterior limb development in vertebrates.
The axolotl is therefore used as a model for the development of limbs in vertebrates.
Androgen, also called androgenic hormone or testoid, is the generic term for any natural or synthetic compound, usually a steroid hormone, that stimulates or controls the development and maintenance of male characteristics in vertebrates by binding to androgen receptors.
" However, Kropotkin did consider cooperation as a feature of the most advanced organisms ( e. g., ants among insects, mammals among vertebrates ) leading to the development of the highest intelligence and bodily organization.
In contrast, the amphioxus and vertebrates show cell determination relatively late in development and cell cleavage is indeterminate.
The blastocyst is a structure formed in the early development of vertebrates.
The development of the meninges and the existence of a defined pia mater was first noted in the vertebrates, and has been more and more significant membrane in the brains of mammals with larger brains.
Embryos of vertebrates have notochords today, as retained a key role in signalling and coordinating development even as it was lost in most adults.
The bibliography is available online to assist in identifying methods and procedures helpful in supporting the development, testing, application, and validation of alternatives to the use of vertebrates in biomedical research and toxicology testing.
NOS signaling is involved in development and in fertilization in vertebrates.
Later on in development, rhombomeres form the rhombocephalon, which forms the hindbrain in vertebrates.
The single ERK5 protein appears to fill a very specialized role ( essential for vascular development in vertebrates ) wherever it is present.
He follows the embryological development of a dog, and its similarities with other vertebrates, before turning to man.
A Dryosaurus hatchling found at Dinosaur National Monument in Utah confirmed that Dryosaurus followed similar patterns of craniofacial development to other vertebrates ; the eyes were proportionally large while young and the muzzle proportionally short.
Neurulation is the development of the nervous system in the vertebrates, at the thickened area above the notochord in ectoderms.
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