Sketchbook- day 7 surface lines

Day 7's challenge concentrated on presenting a 3D drawing using only the surface decoration lines rather than the edge lines.  I decided that my pears did not have sufficient surface decoration and so looked at some tangerines.  The outside skin was dimpled but not really sufficiently lined for this task so I looked at the segments, particularly the lines of pith surrounding them.

I didn't really manage to get a 3D look with just these veins though, so i kind of cheated with shading by wetting the page and the pen lines with water.  The lines didn't really follow the contours of the object so that was probably half of the problem.
I also looked at the inside of the skin and tried to draw that texture with layers of shapes in pen and watercolour pencil.