Table 4. Number of limbs in which growth factors and limb tissue extract induced partial or extensive regeneration across 50% defects in the axolotl fibula at three months post-operation.

	Partial Regeneration	Extensive Regeneration	Total
Seven Factors	1/20	0/20	1/20	(5%)
BMP-4/VEGF	2/20	0/20	2/20	(10%)
BMP-4/HGF	2/20	4/20	6/20	(30%)
Limb Tissue Extract	2/18	4/18	6/18	(33.3%)
Other GF combinations	0/20	0/20	0/20	(0.0%)
Control (scaffold alone)	0/16	0/16	0/16	(0.0%)

Growth factor combinations and blastema extract were tested on a total of 20 limbs each (both hindlimbs of 10 animals), and tissue extract on a total of 18 limbs (both hindlimbs of 10 animals; one animal died). Partial regeneration means that a small amount of cartilage/bone regenerated from one or both cut ends of the fibula. Extensive regeneration means that skeletal regeneration spanned more than 50% of the defect.