BIO380H5 Lecture Notes - Lecture 19: Limb Bud, Central Artery, Apposition
Document Summary
Soon a feedback loop involving fgf-10 and fgf-8 is established, and limb development begins. In early limb development, mesoderm is the primary bearer of the limb blueprint, and ectoderm is only secondarily co-opted into the system. Regulative properties and axial determination: the early limb primordium is a highly regulative system; properties can be summarized with the following experiments. If part of a limb primordium is removed, the remainder reorganizes to form a complete limb. If a limb primordium is split into two halves, and these are prevented from fusing, each half gives rise to a complete limb (the twinning phenomenon). If two equivalent halves of a limb primordium are juxtaposed, one complete limb forms. If two equivalent limb disks are superimposed, they reorganize to form a single limb. In some species, disaggregated limb mesoderm can reorganize and form a complete limb: early fixation of the anteroposterior axis may result from the expression of the transcription factors gli-
