BIOL303 Lecture Notes - Lecture 3: Hedgehog Signaling Pathway, Transforming Growth Factor, Bone Morphogenetic Protein
10 Dec 2016
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Document Summary
Hormones in circulatory system acting from a great distance. Localized production of paracrine factors soluble proteins, peptides or glycoproteins secreted into the extracellular space. Paracrine factor: the signal produced by the inducer usually a secreted protein: instructive and permissive. Inductive interaction in which the signal from the inducing cell is necessary for initiating new gene expression in the responding cell. Inductive interaction in which the responding tissue has already been specified* and needs only an environment that allows the expression of these traits. The ability of a cell to migrate may (cid:396)e(cid:395)ui(cid:396)e a su(cid:271)st(cid:396)ate, let"s sa(cid:455) the signal tells the cell to commence moving but without the substrate there will be no movement even when the signal is present. In other words, it is the underlying mesenchyme telling the upper epithelium what to do: epithelium was competent to receive signals. Instructive and regional: here mesenchyme activates the expression of different sets of genes in the responding epithelial cells.
