Guidepost cells direct and organize these structures. By binding to plexins
Guidepost cells direct and organize these structures. By binding to plexins, semaphorins direct the movement of these structures. In these structures, microtubules and F-actin at the "growth cone" move toward positive stimuli. The Hodgkin-Huxley model was formulated from data taken from the "giant" structure of this kind in squid. The last site of summation prior to this structure occurs at its namesake (*) "hillock." Saltatory conduction takes place at naked sites along this structure known as Nodes of Ranvier. Either oligodendrocytes or Schwann cells supply a substance that insulates these structures. They terminate at synapses. For 10 points, name these often-myelinated long parts of neurons, contrasted with dendrites.