Testicular regulation in nonmammalian vertebrates.
Testicular regulation in nonmammalian vertebrates.
复制标题
非哺乳动物脊椎动物的睾丸调节。
作者：
I. Callard;G. Callard;V. Lance;J. L. Bolaffi;J. Rosset
近代脊椎动物的成功扩散最终取决于它们的生殖周期是否适应它们进化的环境。由于几乎所有的可居住环境都表现出一定程度的波动，因此为了适应这些环境，就必须对生殖周期进行一定的控制，以便在一年中最有利于它们生存的时候繁殖后代。这种对脊椎动物生殖周期的控制要求生物体能够感知环境的变化并相应地改变其生理机能。这是通过调节神经内分泌系统实现的，从鱼类到哺乳动物，神经内分泌系统基本相同，只有微小的变化。脊椎动物的祖先可能已经拥有脑垂体（Barrington，1968），但没有办法知道这个祖先脑垂体是否对生殖过程有任何控制，因为没有可识别的脑垂体的原索动物。虽然有一些证据表明海鞘的神经复合体和性腺之间的关系，（Georges，1976），试图将脊椎动物垂体的前身追溯到被囊动物的这种专门结构（贝里尔，1955年）或轮风琴和哈切克的文昌鱼坑（Barrington，1964）的评论都非常不成功（Dodd，1955; Charniaux-Cotton和Kleinholz，1964;伯尔尼和南迪，1964; Barrington，1968; Olssen，
The successful dispersion of the recent vertebrates has depended ultimately upon the adaptation of their reproductive cycles to the environments in which they evolved. Since almost all habitable environments show some degree of fluctuation, adaptation to these environments has necessitated some control of the reproductive cycle to produce offspring at the time of the year most advantageous to their survival. Such control of the vertebrate reproductive cycle requires that the organism be able to sense changes in the environment and modify its physiology accordingly. This has been accomplished through modulation of the neuroendocrine system, which is basically the same from fish to mammals with only minor variations. It is likely that the ancestral group from which the vertebrates arose already possessed a pituitary gland (Barrington, 1968), but there is no way of knowing whether or not this ancestral pituitary had any control over the reproductive processes, as there are no protochordates with a recognizable pituitary. While there is some evidence of a relationship between the neural complex and the gonads of ascidians (Georges, 1976), attempts to trace the antecedents of the vertebrate pituitary to this specialized structure in tunicates (Berrill, 1955) or the wheel organ and Hatschek’s pit of Amphioxus (Barrington, 1964) have been singularly unsuccessful (reviews by Dodd, 1955; Charniaux-Cotton and Kleinholz, 1964; Bern and Nandi, 1964; Barrington, 1968; Olssen,