The vocal motor neurons of Xenopus laevis: development of sex differences in axon number.
The vocal motor neurons of Xenopus laevis: development of sex differences in axon number.
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非洲爪蟾的发声运动神经元：轴突数量性别差异的发育。
DOI：
10.1002/neu.480210605
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发表时间：
1990
期刊：
影响因子：
--
通讯作者：
Dennison,J
中科院分区：
文献类型：
--
作者：
Kelley,DB;Dennison,J
爪蟾（Xenopus laevis）的喉部肌肉纤维数量的性别差异在变态后发展。为了研究可能的贡献，神经支配这一过程中，我们准备了部分喉神经从蝌蚪阶段56，当性别可以首先区分，通过成年期，并计数轴突的电子显微镜照片。轴突的成年数量是通过轴突添加和丢失的性别分化模式来实现的。轴突数量高，在蝌蚪阶段56和平等的男性和女性，此后，男性有更多的轴突。性别差异在蝌蚪阶段62最明显，因为在阶段59和62之间，雄性的喉轴突数量平均增加了119个神经。超微结构证据与在蝌蚪阶段56和62之间向喉神经添加新轴突的假设一致。女性喉神经轴突的损失大于男性。在蝌蚪阶段56和成年期之间，雄性的轴突总数减少了47%，雌性减少了64%。轴突变性的迹象是目前在两性变态前，但在少年或成年阶段是罕见的。幼蛙的轴突数量与成年蛙的轴突数量没有差异，雄性的轴突数量仍大于雌性。与轴突增加和损失的量相反，轴突损失的时间和有髓鞘轴突的百分比在整个发育过程中对于男性和女性是相同的。因此，喉肌的神经支配的性别差异起源于变态之前，并可能有助于显着的性别差异，肌纤维除了发生之后。
Sex differences in the number of muscle fibers in the larynx of clawed frogs (Xenopus laevis) develop after metamorphosis. In order to examine possible contributions of neural innervation to this process, we prepared sections of the laryngeal nerve from tadpole stage 56, when the sexes can first be distinguished, through adulthood, and counted axons on electron micrographs. The adult number of axons is achieved by a sexually differentiated pattern of axonal addition and loss. Axon numbers are high at tadpole stage 56 and equal for males and females; thereafter, males have more axons. Sex differences are most pronounced at tadpole stage 62 because between stages 59 and 62 the number of laryngeal axons in males increases by an average of 119 per nerve. Ultra‐structural evidence is congruent with the hypothesis that new axons are added to the laryngeal nerve between tadpole stages 56 and 62. The loss of axons from the laryngeal nerve is greater for females than for males. Between tadpole stages 56 and adulthood, overall axon number decreases by 47% in males and by 64% in females. Signs of axonal degeneration are present in both sexes before metamorphosis but are rare at juvenile or adult stages. The numbers of axons in juvenile frogs do not differ from those in adults and continue to be greater in males than in females. In contrast to the amount of axon addition and loss, the timing of axon loss and the percentage of myelinated axons is the same for males and females throughout development. Thus sex differences in the innervation of laryngeal muscle originate before metamorphosis and could contribute to the marked sex differences in muscle fiber addition that occur thereafter.