Meeting Abstract

78.5  Wednesday, Jan. 6  Morphology and histology of the earliest stages of tail regeneration in the leopard gecko, Eublepharis macularius. VICKARYOUS, MK*; ZWEERMAN, CL; University of Guelph; University of Guelph mvickary@uoguelph.ca

Many lizards are able to voluntarily self-detach (autotomize) a portion of the tail as a strategy to escape predation. Autotomy ruptures all the major tissue types of the tail and results in the creation of a relatively large wound. Unlike mammals, the cascade of healing events that follow wounding does not lead to scar formation. Instead, most tail-autotomizing lizards are able to regenerate a functionally equivalent replacement tail. Using the leopard gecko, Eublepharis macularius, we investigated the anatomy and histology of tail loss at multiple intervals beginning shortly after the detachment event through to the initial outgrowth of the new (regenerate) tail. We identify three sequential stages during this timeframe. Stage 1 begins immediately after autotomy and is characterized by retraction of the spinal cord, the collapse of adjacent skin over the wound, and the formation of an exudate clot. In stage 2 a stratified wound epithelium develops deep to the clot, mesenchymal cells begin to proliferate adjacent to the spinal cord, and numerous multinucleated osteoclasts are observed remodelling bone. In stage 3 the clot is lost, thus exposing a thickened wound epithelium (the apical epithelial cap), and angiogenesis begins within the mesenchymal mass. Later an outgrowth of the spinal cord (the ependymal tube) invades the mesenchymal tissue. Available evidence indicates that the leukocytic response to tail loss is limited in duration.