Limb regeneration to digit stages occurs in well‐fed adult newts after hypophysectomy

AbstractExperiments were designed to determine the maximum survival time and extent of limb regeneration of well‐fed adult newts (Notophthal‐mus viridescens) after complete hypophysectomy.Adult newts were either well‐fed or fasted for 3 weeks at which time hypophysectomies were performed. Forelimbs were amputated 5 days posthypophy‐sectomy. Fasted hypophysectomized newts did not survive beyond 4 weeks, and limb regeneration was either absent or abortive. All of the well‐fed newts survived to 3 weeks posthypophysectomy, and even at 6 weeks posthypophy‐sectomy showed 30% survival. In the complete absence of the pituitary gland, many of the fed newts regenerated limbs to digit stages. It is concluded that pituitary hormones are not an absolute requirement for limb regeneration of adult newts. Newts in good nutritional condition at the time of hypophysectomy survive longer and their limbs regenerate to more advanced stages.