The role of androgen in declining regenerative capacity during morphogenesis of the Platypoecilus maculatus gonopodium

Abstract

It has been shown previously (Grobstein, '47) that cluring morphogenesis of the Platypoecilus maculatus gonopodium regenerative capacity sharply declines. Whereas the immature anal fin or the anal fin of the adult female regenerates completely following amputation, the adult male aual fin, modified under the iilfiuence of androgen into a copulatory organ, regenerates abortively and atypically. It is the purpose of the present paper to describe the results of experiments to elucidate the role of androgen in this decline of regenerative capacity.The problem of the significance of morphogeiietic hormones in decline of regenerative capacity arose first in the study of anuran regeneration. As will be pointed out, conflicting statements have been made about the relative importance of local and hormonal factors in the rapid decline of regenerative capacity which occurs at the time of anuraii metamorphosis. There seems to be some advantage in studying the question in another organism. The observation that the poeciliid gonopodium undergoes reduction of regenerative capacity during its androgen-induced morphogenesis (Ibid) suggests it as a suitable test objective f o r this purpose.The experiments to be reported sought to answer two main questions. First, is the decline in regenerative capacity di- 313

The biology of senescence

“…Pituitary growth hormone of mammalian origin is able to promote the growth offish (Swift, 1954). The relation between morphogenesis under the influence of gonadal hormones and loss of regenerative power has special interest in gerontology. Grobstein (1947) found that when the gonopodium of poeciliid fish differentiates, under the influence of androgens, regenerative power is lost: he stresses the analogy between this process and the loss of regenerative capacity in the developing anuran limb. Such a change need not depend upon irreversible loss of cellular capacity to grow-this does The Mechanisms of Senescence not appear to be the case in amphibian limbs (Borssuk, 1935;Polezaiev and Ginsburg, 1939) but the physiological loss of repair-power may be as complete, so far as the intact animal is concerned, as is the loss of moulting-power in Rhodnius once the evocator is lost.…”

Effects of gene dosage and hormones on the expression of Dr in the platyfish,Xiphophorus maculatus(Poeciliidae)

“…Immature males were castrated according to the method of Grobstein (1947). After the operation the fish are placed in conditioned aquarium water to which commercial sea salts have been added to make a 0-9% salt solution.…”

Inter-organ communication during tissue regeneration

“…Examples also exist demonstrating that transitions in tissue regenerative capacity during development are associated with a peak of hormone production or prolonged elevation of hormone levels in animals (Alberch et al, 1986;Hirose et al, 2019;Larras-Regard et al, 1981). The inability of tissue to regenerate following hormone exposure is not only limited to tissue that has undergone an injury; tissue exposed to high levels of hormones during development may also lack the ability to regenerate later in life (Grobstein, 1947), suggesting that transient exposure to hormone signals can sculpt future regenerative responses to injury.…”