Biology 3338A Lecture Notes - Lecture 23: Sonic Hedgehog, Limb Bud, Zone Of Polarizing Activity
22 Aug 2016
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Top shows fingers numbered with 1 anterior-most (thumb) and then down to 5 posterior-most (little finger) Different levels of bmp regulates different identities of fingers = thumb looks different from index finger because they have different bmp levels. Interfering with bmp levels interferes with digit identities. Experiment shows adding bmp beads to increase bmp conc changes identities of digits to be more anterior". Specific levels of bmp in between digits facilitates specific identities of digits. Talked about p-d and a-p axes now d-v axis. As limb bud grows out, it takes body axes with it so dorsal becomes back of hand vs. ventral becomes palm. Reason joints bend only one way is because wnt7a dictates which side is dorsal. Hands especially have huge d-v asymmetry palm very different from back of hand. Interfering with d-v = huge developmental problems wrt vasculature/innervation in limbs. This is because important bvs and nerves located on back of hand since palms get cut easily.
