Kelley D B, Fenstemaker S, Hannigan P, Shih S
Department of Biological Sciences, Columbia University, New York, New York 10027.
J Neurobiol. 1988 Jul;19(5):413-29. doi: 10.1002/neu.480190503.
In the clawed frog (Xenopus laevis), motor neurons in cranial nerve nucleus IX-X control contraction of laryngeal muscles responsible for sexually dimorphic vocal behaviors. We examined sex differences in dendritic arbors of n.IX-X cells using the Golgi-Cox method. Three morphological classes of somal types (ovoid, triangular, and elongate) are present in similar frequencies in n.IX-X of both males and females. The male n.IX-X neuron is a more complex and hypertrophied version of the female n.IX-X cell. The number of primary dendrites is the same for both sexes, but males have more total dendritic segments. The overall dendritic length of male n.IX-X neurons is two to three times that of the female. Males have longer dendritic segments between all branch points. Male and female frogs differ in levels of circulating androgens; neurons of n.IX-X are targets for androgenic steroids. To determine if androgen can affect dendritic morphology in adult females, we examined Golgi-impregnated cells in n.IX-X from ovariectomized females treated with testosterone for 1 month. The total number of dendritic segments was reduced by androgen treatment due to reduction in the number of higher order dendritic segments; the number of primary dendritic segments was unchanged. Androgen treatment may induce resorption of higher order dendritic branches. The overall dendritic length of androgen-treated female n.IX-X neurons was unchanged, and dendritic segments were longer. Thus, although androgen can alter dendrites of n.IX-X cells in adult females, this short-term treatment does not produce a masculine dendritic architecture.
在非洲爪蟾（非洲爪蟾）中，第IX - X对脑神经核中的运动神经元控制负责两性异形发声行为的喉部肌肉收缩。我们使用高尔基 - 考克斯方法研究了第IX - X对脑神经核细胞树突分支的性别差异。在雄性和雌性的第IX - X对脑神经核中，三种形态类型的体细胞（卵圆形、三角形和细长形）出现的频率相似。雄性第IX - X对脑神经核神经元是雌性第IX - X对脑神经核细胞更复杂且肥大的版本。两性的初级树突数量相同，但雄性的总树突段更多。雄性第IX - X对脑神经核神经元的总树突长度是雌性的两到三倍。雄性在所有分支点之间的树突段更长。雄性和雌性青蛙的循环雄激素水平不同；第IX - X对脑神经核的神经元是雄激素类固醇的靶标。为了确定雄激素是否会影响成年雌性的树突形态，我们检查了用睾酮处理1个月的去卵巢雌性的第IX - X对脑神经核中经高尔基染色的细胞。雄激素处理使树突段总数减少，原因是高阶树突段数量减少；初级树突段数量未变。雄激素处理可能会诱导高阶树突分支的吸收。经雄激素处理的雌性第IX - X对脑神经核神经元的总树突长度未变，且树突段更长。因此，尽管雄激素可以改变成年雌性第IX - X对脑神经核细胞的树突，但这种短期处理不会产生雄性化的树突结构。
