On a an arboreal solution to the problem of the ever-growing forest of cell types:

"The end proposal is for a three-dimensional tree representation where the axes are cell lineage, differentiation state, and time, with computational techniques applied to determine when you branch things off (i.e., setting things up for maximum information gain in the display)."

https://www.science.org/content/blog-post/organizing-our-thoughts-about-cells-finally