Hormonal dependence of tail regeneration in the lizard Anolis carolinensis

Abstract

Removal of the pars distalis several days before the amputation of the tail in Anolis carolinensis delays blastema formation and virtually abolishes tail regeneration. Hypophysectomy on, or several days after, tail amputation does not delay blastema formation but tail growth is largely abolished. If lizards are hypophysectomized after the blastema has formed and the tail has begun to elongate, the rate of tail regeneration is greatly reduced within a few days.Injection of a combination of adenohypophysial hormones (growth hormone, prolactin, gonadotropin, and thyrotmpin) restored tail regeneration to near normal levels in hypophysectomized lizards.A quantitative relationship was evident between the amount of pars distalis removed and the rate of tail regeneration. However, there was no apparent relationship between the region of the gland removed and regeneration, indicating that tail regeneration is probably dependent on a combination of several pituitary hormones.

A Histological Comparison of the Original and Regenerated Tail in the Green Anole, Anolis carolinensis

“…The process of tail regeneration has been described in a number of lizard species, with several studies focusing on the process in A. carolinensis (Jamison, 1964; Cox, 1968; Maderson and Licht, 1968; Simpson, 1968, 1970; Licht and Howe, 1969; Zika, 1969; Egar et al, 1970; Maderson and Salthe, 1971; Chlebowski et al, 1973; Turner and Singer, 1973; Bellairs and Bryant, 1985; Simpson and Duffy, 1994; Alibardi, 1995a, b, 2010; Alibardi and Toni, 2005). However, very little data exists regarding the fully regenerated tail, as most accounts focus on earlier stages of regeneration.…”

“…Lizards have evolved the remarkable abilities to both autotomize, or self‐amputate, their tails when threatened (Vitt, 1981; Reichman, 1984; Bellairs and Bryant, 1985; Goss, 1987; Arnold, 1988; Maginnis, 2006) and then to regenerate a functional tail (reviewed in Alibardi, 2010). Members of the Polychrotidae, particularly the green anole, Anolis carolinensis , have been particular favorites for tail regeneration studies (Jamison, 1964; Cox, 1968; Maderson and Licht, 1968; Simpson, 1968, 1970; Licht and Howe, 1969; Zika, 1969; Egar et al, 1970; Maderson and Salthe, 1971; Chlebowski et al, 1973; Turner and Singer, 1973; Bellairs and Bryant, 1985; Simpson and Duffy, 1994; Alibardi and Toni, 2005; Alibardi, 1995a, b, 2010). A. carolinensis is found throughout the southeastern United States and this made it a readily available lizard model for a wide range of studies, including research focusing on developmental and reproductive biology, behavioral ecology, and neurobiology.…”

Tail Regeneration in the Scincid Lizard, Mabuya carinata, related to Breeding Seasons and Thyroid Activity

“…Literature on environmental and hormonal control on regeneration is more extensive with respect to amphibians than to reptiles. A few studies carried out on reptiles have not yielded any conclusive inferences and, moreover, these studies are all pertaining to temperate species (Licht, 1967;Licht and Jones, 1967 ;Maderson and Licht, 1968;Licht and Howe, 1969;Turner and Tipton, 1971;Turner, 1972).…”