Re-establishment of forelimb regeneration in adult hypophysectomized Diemictylus (Triturus) viridescens given frog anterior pituitary extract.

Abstract

AbstractAdults of Diemictylus (Triturus) viridescens were included in this work which was designed to test to what extent a limb of an hypophysectomized animal can regenerate when given frog anterior pituitary extract. The results are based on 123 animals which comprise six experimental, three experimental control, one sham control and one normal control series.Consideration was given to the essential relationship between the anterior pituitary gland and forelimb regeneration and whether or not daily injections of adenohypophysis extracts of adult Rana pipiens, frogs (which do not regenerate limbs) could promote normal limb regeneration and also long‐term survival in adult hypophysectomized Diemictylus. In this approach, hypophysectomy was followed by a period of five days (to minimize remaining circulatory levels of hormones) before the right forelimb was amputated. From the time of amputation daily replacement therapy of frog pituitary extract was administered until the day of fixation. In 26 out of 28 cases, from series 2 to 5, normal regeneration ensued. In one series (no. 6), forelimb amputation was performed five days post‐hypophysectomy, however, injections of extracts were delayed for ten days after amputation (15 days post‐hypophysectomy) in order to determine whether or not limb regeneration could be re‐established in an essentially stumping forelimb of a dying animal. Retarded and somewhat abnormal regeneration occurred in ten out of the fifteen cases of series 6; the five non‐regenerating cases displayed precocious dermal wound healing.These results demonstrate that the normal, advanced, forelimb regeneration, as well as the long‐term survival, of our adult, hypophysectomized Diemictylus was due, directly or indirectly, to the presence of a continuous, hormonal background provided by the adenohypophyseal hormones of frog.