Applying the Value Sphere to a Medical Illustration

I've heard that good artists are well-versed in the fundamentals. So, I've been revisiting some familiar concepts to refresh myself. First, I revisited the value sphere. After creating the sphere, I immediately applied it to the current illustration that I am working on. It was great to see the direct translation! 

Left: Sketch pad with value sphere. Right: Illustration of interconnected osteocytes.

This is the original post that I made about this exercise. It explains all the little notes in my pad!