Licht P
Prog Clin Biol Res. 1986;205:95-114.
Perhaps one should be impressed by the basic generality of many of the features of the mammalian HHG system. The applicability of this model to other groups argues for the generally conservative nature of the basic organization of the reproductive endocrine system. Even in cases where exceptions are apparent, we must be cognizant of the relatively narrow base of mammalian species on which the classical mammalian model is built. While reference to the mammalian system provides a useful first approach to studies on new groups, in view of the many exceptions in details of this system, it is important that we avoid undue constraints that might be imposed by the the mammalian model. In this connection it would seem advisable to test each principle carefully before assuming that it exists or is as important as in mammals. A particularly significant issue in this regard is the question of temporal organization of endocrine secretions: Both the existence and relative importance of discontinuous, pulsatile, stimulation must be explored in more groups. It must be emphasized that past experience has already shown us that a simple phylogenetic approach is not likely to provide a clear pattern for the similarities and differences in the reproductive endocrine system. Thus, we should not be too hasty in our extrapolations of data, even among closely related species.
或许人们应该对哺乳动物下丘脑 - 垂体 - 性腺（HHG）系统许多特征的基本普遍性印象深刻。该模型对其他类群的适用性表明生殖内分泌系统基本组织具有普遍保守的性质。即使在明显存在例外的情况下，我们也必须认识到经典哺乳动物模型所基于的哺乳动物物种基础相对狭窄。虽然参考哺乳动物系统为研究新类群提供了有用的初步方法，但鉴于该系统细节存在诸多例外，重要的是我们要避免可能由哺乳动物模型施加的过度限制。在这方面，在假设某一原理存在或与哺乳动物中一样重要之前，仔细检验每一个原理似乎是明智的。在这方面一个特别重要的问题是内分泌分泌的时间组织问题：必须在更多类群中探索不连续、脉冲式刺激的存在及其相对重要性。必须强调的是，过去的经验已经向我们表明，简单的系统发育方法不太可能为生殖内分泌系统的异同提供清晰的模式。因此，即使在亲缘关系密切的物种之间，我们在推断数据时也不应过于草率。
