6>LIMb develoopment Flashcards
Limb Bud
A localized protrusion of mesodermal and ectodermal cells where a limb will form during embryogenesis, initiated by growth factors like FGF10.
Apical Ectodermal Ridge (AER)
A structure at the tip of a limb bud that produces growth factors (e.g., FGF8) to regulate limb outgrowth in the proximal-distal axis.
apical=apex=at the tip
Lmx-1b Gene
A gene encoding a transcription factor needed for dorsal limb patterning; mutations result in Nail-Patella Syndrome.
Zone of Polarizing Activity (ZPA)
A group of cells at the posterior margin of a limb bud that secretes Sonic Hedgehog (SHH) protein to regulate anterior-posterior limb patterning.
Fibroblast Growth Factor (FGF10)
A growth factor secreted by intermediate mesoderm cells to initiate limb bud formation by inducing mesodermal proliferation and ectodermal FGF8 secretion.
Sonic Hedgehog (SHH)
a signaling protein produced in the zone of polarizing activity (ZPA) that acts as a morphogen, forming a gradient to guide digit formation and anterior-posterior limb patterning.”
Hox Genes
A group of transcription factors that control segment identity and regulate limb structure formation, such as scapulas and digits.
Split-Hand/Split-Foot Syndrome
A genetic condition caused by mutations in genes like e.g DLX5 leading to malformations where the middle fingers or toes are absent.
Polydactyly
A congenital condition where a person has extra digits due to mutations in genes like GLI3 or ZNF141 that alter SHH gradient or its signaling.
Thalidomide
A teratogen that inhibits the protein cereblon, disrupting limb development by interfering with FGF8 production in the AER.
A teratogen is an agent, such as a chemical, drug, infection, or radiation, that can cause malformations or functional defects in a developing embryo or fetus.
