Goldman S A, Nottebohm F
Proc Natl Acad Sci U S A. 1983 Apr;80(8):2390-4. doi: 10.1073/pnas.80.8.2390.
The vocal control nucleus designated HVc (hyperstriatum ventrale, pars caudalis) of adult female canaries expands in response to systemic testosterone administration, which also induces the females to sing in a male-like manner. We became interested in the possibility of neurogenesis as a potential basis for this phenomenon. Intact adult female canaries were injected with [3H]thymidine over a 2-day period. Some birds were given testosterone implants at various times before thymidine. The birds were sacrificed 5 wk after hormone implantation, and their brains were processed for autoradiography. In parallel control experiments, some birds were given implants of cholesterol instead of testosterone. All birds showed considerable numbers of labeled neurons, glia, endothelia, and ventricular zone cells in and around HVc. Ultrastructural analysis confirmed the identity of these labeled neurons. Cholesterol- and testosterone-treated birds had similar neuronal labeling indices, which ranged from 1.8% to 4.0% in HVc. Thus, neurogenesis occurred in these adults independently of exogenous hormone treatment. Conversely, both glial and endothelial proliferation rates were markedly stimulated by exogenous testosterone treatment. We determined the origin of the thymidine-incorporating neurons by sacrificing two thymidine-treated females soon after their thymidine injections, precluding any significant migration of newly labeled cells. Analysis of these brains revealed no cells of neuronal morphology present in HVc but a very heavily labeled ventricular zone overlying HVc. We conclude that neuronal precursors exist in the HVc ventricular zone that incorporate tritiated thymidine during the S phase preceding their mitosis; after division these cells migrate into, and to some extent beyond, HVc. This ventricular zone neurogenesis seems to be a normally occurring phenomenon in intact adult female canaries.
成年雌性金丝雀的发声控制核团HVc（尾侧腹侧纹状体）会因全身性睾酮给药而扩大，这也会诱导雌性以类似雄性的方式唱歌。我们对神经发生作为这一现象的潜在基础的可能性产生了兴趣。完整的成年雌性金丝雀在两天内注射了[3H]胸腺嘧啶核苷。一些鸟类在注射胸腺嘧啶核苷之前的不同时间植入了睾酮。在激素植入5周后处死这些鸟类，并对它们的大脑进行放射自显影处理。在平行对照实验中，一些鸟类植入的是胆固醇而非睾酮。所有鸟类在HVc及其周围都显示出大量标记的神经元、神经胶质细胞、内皮细胞和脑室区细胞。超微结构分析证实了这些标记神经元的身份。胆固醇处理组和睾酮处理组的鸟类具有相似的神经元标记指数，在HVc中为1.8%至4.0%。因此，这些成年鸟类的神经发生与外源性激素处理无关。相反，外源性睾酮处理显著刺激了神经胶质细胞和内皮细胞的增殖率。我们通过在注射胸腺嘧啶核苷后不久处死两只经胸腺嘧啶核苷处理的雌性金丝雀来确定掺入胸腺嘧啶核苷的神经元的起源，这排除了新标记细胞的任何显著迁移。对这些大脑的分析显示，HVc中不存在神经元形态的细胞，但在HVc上方有一个标记非常强烈的脑室区。我们得出结论，HVc脑室区存在神经元前体细胞，并在有丝分裂前的S期掺入氚标记的胸腺嘧啶核苷；分裂后，这些细胞迁移到HVc内，并在一定程度上超出HVc。这种脑室区神经发生似乎是完整成年雌性金丝雀中正常发生的现象。
