Nixdorf-Bergweiler B E
Department of Neurophysiology, University of Cologne, Germany.
J Comp Neurol. 1996 Nov 18;375(3):445-56. doi: 10.1002/(SICI)1096-9861(19961118)375:3<445::AID-CNE7>3.0.CO;2-2.
Song control regions in passerine birds are known to be sexually dimorphic in the adult brain in species like zebra finches in which most males sing whereas females do not. As a first step toward the analysis of the establishment of anatomical sex differences, volumetric changes of Nissl-defined song control regions in the forebrain of the zebra finch have been quantified in both sexes at 10-day intervals starting at day 10 posthatching. In males, the Nissl-defined volume of the high vocal center, the robust nucleus of the archistriatum, and area X of the lobus parolfactorius increased with age, reaching the adult value at 60, 50, and at 40 days posthatching, respectively. The lateral magnocellular nucleus of the anterior neostriatum increased in volume until 20 days and then gradually decreased to reach the adult value at about 40 days. Whereas area X is absent in females, the high vocal center, the robust nucleus of the archistriatum, and the lateral magnocellular nucleus of the anterior neostriatum were detectable throughout development and in adulthood. In contrast to the males, volumes of the high vocal center and of the robust nucleus of the archistriatum decreased in females between 10 and 40 days posthatching (58% and 61%, respectively), when adult values were reached. Contrary to the development of these two nuclei in females, the volumetric development of the lateral magnocellular nucleus of the anterior neostriatum was very similar in both sexes. Females began with a smaller lateral magnocellular nucleus of the anterior neostriatum at 10 days posthatch, which led to a sexual dimorphism in juvenile stages, but there was no sexual dimorphism of volume size in adult brains.
在诸如斑胸草雀等雀形目鸟类中，已知成年大脑中的鸣唱控制区域存在性别二态性，其中大多数雄性会唱歌而雌性不会。作为分析解剖学性别差异形成的第一步，从孵化后第10天开始，每隔10天对斑胸草雀前脑尼氏染色定义的鸣唱控制区域的体积变化进行了两性定量分析。在雄性中，尼氏染色定义的高发声中枢、古纹状体粗核和嗅觉叶X区的体积随年龄增加，分别在孵化后60天、50天和40天达到成年值。新纹状体前部外侧大细胞核的体积在20天前增加，然后逐渐减少，在大约40天达到成年值。雌性没有X区，而高发声中枢、古纹状体粗核和新纹状体前部外侧大细胞核在整个发育过程和成年期都可检测到。与雄性不同，雌性的高发声中枢和古纹状体粗核的体积在孵化后10至40天（分别为58%和61%）减小，此时达到成年值。与雌性这两个核的发育相反，新纹状体前部外侧大细胞核的体积发育在两性中非常相似。雌性在孵化后10天开始时新纹状体前部外侧大细胞核较小，这导致了幼年期的性别二态性，但成年大脑中体积大小不存在性别二态性。
