van Mier P
Department of Medical Physics and Biophysics, University of Nijmegen, The Netherlands.
Acta Biol Hung. 1988;39(2-3):161-77.
The development of early swimming in Xenopus occurs early during the embryonic period and within a few hours. Between stages 25 and 33 the central nervous system reaches a state of 'critical mass' at which the for swimming necessary body structures have partly developed, thus enabling the embryo to move through the water. The pattern of undulatory body movements is formed within the pattern generators in the central nervous system (CNS) involving different types of neurons in the spinal cord and brainstem. Tailswimming in Xenopus embryos can be evoked by tactile stimuli, light or vibrations. Here the development of brainstem-spinal connections and their possible role in swimming caused by external stimuli will be discussed. It is now clear that reticulospinal neurons are among the first neurons that differentiate within the CNS, their axons enter the spinal cord when the first swimming movements occur, that they are active in a motoneuron-like fashion, during--and involved in the control of early tailswimming. Among the reticulospinal neurons only the Mauthner cell seems to serve a command function.
非洲爪蟾早期游泳行为的发展发生在胚胎期的早期阶段，且在数小时内就会出现。在第25至33阶段之间，中枢神经系统达到一种“临界质量”状态，此时，用于游泳的必要身体结构已部分发育完成，从而使胚胎能够在水中移动。波动式身体运动模式是在中枢神经系统（CNS）的模式发生器内形成的，涉及脊髓和脑干中不同类型的神经元。非洲爪蟾胚胎的摆尾游泳可由触觉刺激、光线或振动诱发。在此，将讨论脑干 - 脊髓连接的发育及其在外部刺激引起的游泳行为中可能发挥的作用。现在已经清楚，网状脊髓神经元是中枢神经系统中最早分化的神经元之一，当首次出现游泳运动时，它们的轴突进入脊髓，它们以类似运动神经元的方式活动，在早期摆尾游泳期间并参与对其的控制。在网状脊髓神经元中，似乎只有莫纳细胞发挥着指令功能。
