Table I.

Comparison of cell density in various tumor models.

Tumor model	Cell line	Cell type	Cell packing density (cells/µm3)	Growth period (days)	Ref.
New 3D microfluidic-based tumor model	B16.F10	Mouse melanoma	3.35 × 10−4 ±0.73 × 10−4	0
			2.78 × 10−4 ±0.16 × 10−4	0.5	This study
Spheroid model	EMT6/Ro	Mouse Mammary carcinoma	1.7 × 10−4	4–7	Freyer (1988)
	MEL28	Human melanoma	1.2 × 10−4	4–7
Multicellular layer model	HCT-8	Human colon carcinoma	0.79 × 10−4	5	Grantab et al. (2006)
In vivo tumor	B16.F10	The same as above	5.69 × 10−4	—a	Stephens and Peacock, (1978)
In vivo tumor	B16.F10	The same as above	1.94 × 10−4	7–10	Mossop et al. (2006)
In vivo tumor	4T1	Mouse mammary carcinoma	3.84 × 10−4	7–10	Mossop et al. (2006)

^aCell density was quantified when tumor size reached approximately 0.1 g.