Neither testicular androgens nor embryonic aromatase activity alters morphology of the neural song system in zebra finches.
Neither testicular androgens nor embryonic aromatase activity alters morphology of the neural song system in zebra finches.
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DOI：
10.1095/biolreprod55.5.1126
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发表时间：
1996-11
影响因子：
3.6
通讯作者：
J. Wade;M. L. Springer;J. Wingfield;A. Arnold
中科院分区：
文献类型：
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作者：
J. Wade;M. L. Springer;J. Wingfield;A. Arnold
在斑马雀身上存在着各种各样的性二态现象，无论是在中枢神经系统还是在外周。例如，雄性斑马雀向雌性鸣叫，而雌性斑马雀通常不唱歌。同时，控制歌唱的大脑区域包含各种偏向于男性的性别二型性，而且男性的发声器官(空洞)比女性的大。人们认为，这些性别差异中的一部分，如果不是全部的话，是由发育中的鸟类的睾丸和卵巢分泌的不同激素造成的。然而，改变鸟类孵化后的激素环境对性别分化的影响一直是模棱两可的。我们发现，用一种有效的芳香酶抑制剂法洛唑治疗雌性斑雀胚胎，除了诱导正常的卵巢组织外，还可以诱导睾丸组织发育。这项研究证明了女性睾丸组织的功能，表明它在成年后分泌雄激素，产生精子，并导致对雄激素敏感的空洞扩大。然而，这种功能性的睾丸组织对女性的神经歌唱系统没有影响；大脑区域仍然完全是女性的。因此，这些结果表明，内分泌活跃的睾丸组织本身并不是斑雀鸣叫系统中显著的形态性别差异的原因。
A variety of sexual dimorphisms exist in zebra finches, both in the central nervous system and in the periphery. For example, male zebra finches sing to court females, whereas females do not normally sing. In parallel, the brain regions that control song contain a variety of male-biased sexual dimorphisms, and the vocal organ (syrinx) is larger in males than in females. It is thought that some, if not all, of these sex differences are caused by differential hormone secretion by the testes and ovaries of developing birds. However, the effects on sexual differentiation of altering the hormonal environment of birds after hatching have been ambiguous. We have found that treating embryonic female zebra finches with fadrozole, a potent aromatase inhibitor, can induce testicular tissue to develop in addition to normal ovarian tissue. This study documents the function of that testicular tissue in females by showing that it secretes androgens in adulthood, produces sperm, and causes the androgen-sensitive syrinx to enlarge. However, that functional testicular tissue has no effect on the neural song system of females; the brain regions remain completely feminine. Therefore, these results suggest that endocrinologically active testicular tissue alone is not responsible for the dramatic morphological sex differences in the zebra finch song system.