Table 1 Summary of key gross morphological and histological criteria used to define the stages of tail regeneration in Eublepharis macularius

→ autotomized vertebra exposed but no adjacent muscle or connective tissue retraction

I

→ spinal cord retracts within neural canal and is capped distally by a small blood clot

→ integument begins to collapse around the wound site

→ autotomized vertebra exposed and adjacent muscles and connective tissues retracted

→ large clot caps entire wound surface

II

→ integument collapsed around wound site

→ wound epithelium proliferates and begins to spread across autotomy surface deep to clot

→ blastema appears between retracted spinal cord and overlying clot

→ first appearance of multinucleated osteoclasts and chondroclasts adjacent to autotomized vertebra

→ clot is lost and the complete wound epithelium is exposed

→ wound epithelium continues to proliferate and thicken

III

→ apical epithelial cap forms

→ blastema spreads beyond neural canal to cap distal end of the tail deep to wound epithelium

→ angiogenesis begins within the blastema

→ ependymal tube and axons from the dorsal root ganglia of the original tail begin to grow into blastema

IV

→ regenerating tail is dome-shaped and wider than long (length: diameter is less than 0.5)

→ regenerating tail is an elevated dome and wider than long (length: diameter is greater than 0.5 but less than 1.0)

V early

→ earliest appearance of presumptive cartilaginous skeleton around the ependymal tube

→ muscle tissue begins to differentiate

→ regenerating tail is an elevated dome and wider than long (length: diameter is greater than 0.5 but less than 1.0)

V late

→ keratinization and the formation of scales begins within the epidemis

→ first expression of Sox9 in cartilage cells of regenerating cartilage cone and original tail cartilage

→ regenerating tail is a tapering cone approaching a length: width of 1.0

VI

→ first appearance of the differentiated dermis

→ differentiation of cartilage, muscle and adipose tissue nearing completion

→ regenerating tail is a tapering cone longer than wide (length: diameter is greater than 1.0)

VI

→ proximal portion of the regenerate tail is equal in diameter to the distal portion of original tail

→ pigmentation begins