From cellular + -ity.
cellularity (countable and uncountable, plural cellularities)
- (medicine) The number and type of cells in a given tissue
1994, Stanley Hoppenfeld, Michael S. Zeide, “Chondrosarcoma”, in Orthopaedic Dictionary[1], →ISBN, page 61:Microscopically, there are cartilaginous cells with increased cellularity and pleomorphism in comparison to benign tumors.