Structure formed early in vertebrate limb development
Limb bud
Details
Precursor
lateral plate mesoderm
Identifiers
Latin
gemmae membrorum
MeSH
D018878
TE
bud_by_E5.0.3.0.0.0.5 E5.0.3.0.0.0.5
Anatomical terminology
[edit on Wikidata]
The limb bud is a structure formed early in vertebrate limb development. As a result of interactions between the ectoderm and underlying mesoderm, formation occurs roughly around the fourth week of development.[1] In the development of the human embryo the upper limb bud appears in the third week and the lower limb bud appears four days later.[2]
The limb bud consists of undifferentiated mesoderm cells that are sheathed in ectoderm.[3] As a result of cell signaling interactions between the ectoderm and underlying mesoderm cells, formation of the developing limb bud occurs as mesenchymal cells from the lateral plate mesoderm and somites begin to proliferate to the point where they create a bulge under the ectodermal cells above.[4] The mesoderm cells in the limb bud that come from the lateral plate mesoderm will eventually differentiate into the developing limb's connective tissues, such as cartilage, bone, and tendon.[3] Moreover, the mesoderm cells that come from the somites will eventually differentiate into the myogenic cells of the limb muscles.[3]
The limb bud remains active throughout much of limb development as it stimulates the creation and positive feedback retention of two signaling regions: the apical ectodermal ridge (AER) and the zone of polarizing activity (ZPA) with the mesenchymal cells.[3] These signaling centers are crucial to the proper formation of a limb that is correctly oriented with its corresponding axial polarity in the developing organism. Research has determined that the AER signaling region within the limb bud determines the proximal-distal axis formation of the limb using FGF signals.[5] ZPA signaling establishes the anterior-posterior axis formation of the limb using Shh signals.[6] Additionally, though not known as a specific signaling region like AER and ZPA, the dorsal-ventral axis is established in the limb bud by the competitive Wnt7a and BMP signals that the dorsal ectoderm and ventral ectoderm use respectively.[7][8] Because all of these signaling systems reciprocally sustain each other's activity, limb development is essentially autonomous after these signaling regions have been established.[3]
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The limbbud is a structure formed early in vertebrate limb development. As a result of interactions between the ectoderm and underlying mesoderm, formation...
bulge out, forming a limbbud. Fibroblast growth factor (FGF) induces the formation of an organizer at the end of the limbbud, called the apical ectodermal...
each limbbud and acts as a major signaling center to ensure proper development of a limb. After the limbbud induces AER formation, the AER and limb mesenchyme—including...
developing limbbud to form along the anterior/posterior axis. Limbbud is undifferentiated mesenchyme enclosed by an ectoderm covering. Eventually, the limb bud...
LBH may refer to: Late Biblical Hebrew LBH (gene) London Borough of Hackney London Borough of Haringey London Borough of Harrow London Borough of Havering...
and proliferate to create the limbbud. The lateral plate cells produce the cartilaginous and skeletal portions of the limb while the myotome cells produce...
deformation results from mechanical disruption of the cells involved in limbbud formation during the amphibian larval stage. R. ondatrae is a digenetic...
lobe-finned fish, and tetrapods. They are characterised by prominent muscular limbbuds (lobes) within their fins, which are supported by articulated appendicular...
into 3 sections, the anterior limbbud formation, the posterior limbbud formation and the non limb forming wall. The bud forming sections grow in size...
patterning is often found in combination with other patterns: vertebrate limb development is one of the many phenotypes exhibiting Turing patterning overlapped...
This causes ectopic SHH expression in the anterior of the developing limbbud, leading to increased tissue growth and digits. While the feet of the Silkie...
have traces of highly reduced, vestigial hind limbs. Python embryos even have fully developed hind limbbuds, but their later development is stopped by the...
the absence of limbbud initiation, but rather arrest of limbbud development. Limbbuds develop normally in cetacean embryos. Limbbuds progress to the...
controls organogenesis and the organization of the central nervous system, limbs, digits and many other parts of the body. Sonic hedgehog is a morphogen...
development begins with interzone condensation of a Collagen II positive limbbud at the future joint site. This is followed by definition of specific cellular...
inducing the limbbud, then inducing and maintaining sonic hedgehog expression in the established limbbud promoting outgrowth of the limb. Evidence for...
study on limb evolution shows that the TAD at the 5’ of the HoxD gene cluster in tetrapod genomes drives its expression in the distal limbbud embryos...
expression. The encoded protein plays a major role in limb development, specifically during limbbud initiation. For instance, in chickens Tbx4 specifies...
Starting during the sixth week, as each limbbud continues to grow and elongate, areas of mesenchyme within the bud begin to differentiate into the hyaline...
time-dependent manner. The morphogen sonic hedgehog (Shh), for example, acts on limbbud and neural progenitors to induce expression of a set of homeodomain-containing...
"Opposing functions of the ETS factor family define Shh spatial expression in limbbuds and underlie polydactyly". Developmental Cell. 22 (2): 459–67. doi:10...
blood vessels in developing limbbuds. Retinoic acid (RA) is significant in embryonic development. It induces the function of limb patterning of a developing...
These genomic regions regulate proliferation and differentiation in the limbbud, and can lead to phenotypic anomalies, including polysyndactyly, if mutated...
to be a result of a wedge-shaped defect of the apical ectoderm of the limbbud (AER: apical ectodermal ridge). Polydactyly, syndactyly and cleft hand...
development of the vertebrate limb. The classic experiments of Saunders and Gasseling in 1968 on the development of the chick limbbud formed the basis of the...
rather than conventional internal organs, as they develop from limbbuds before the buds flatten into segmented lamellae. Book gills are still present...
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