Looks very nice! If I may make a recommendation - if you're using Illustrator CS5, use a stroke and the width tool for outlines - they come out much smoother than trying to trace around both sides of the outline.
You know, I totally forgot about that tool (it was in an early chapter....). What I did on her was to stroke the cells and then outline the strokes and tweek the output of that in order to give it more of a dynamic flowing look. Which is really not the best method when you can use the width tool . Thanks, that's very good advice and I'll be sure to employ that on my next vector.