Studies on Dendroarchitecture and Dendrogenesis of Spinal Motor Meuron Pool with a New Labeling Technique

用辣根过氧化物酶标记霍乱毒素B亚基的方法，研究了支配特定后肢肌肉的运动神经元在鸡脊髓内的树突构筑。髂胫肌和股胫后肌的运动神经元池分别位于腰骶段(LS)1~4和1~3的外侧运动柱的背外侧。尽管股胫骨MNP的树突延伸比髂胫骨后MNP少且短，但两种MNP的树突分布模式非常相似。树突轮廓均匀分布在白质和灰质中。髂胫后肌的MNP呈树枝状，向四面八方延伸。大量树突穿透白质，许多树突到达外侧和腹侧穹隆的软膜表面，向背内侧方向的树突到达背角的底部。髂腓(LS4-7)和尾屈肌(LS6-8)的mNPs均有树突，沿外侧运动柱的侧缘和腹缘延伸。根据这些观察，我们得出结论：支配鸡不同后肢肌肉的MNPs树突的分布有很大的差异。

Dendroarchitecture of motoneurons innervating specific hindlimb muscles was studied in the chick spinal cord by the use of intramuscular injections of horseradish peroxidase conjugated with cholera toxin subunit B. Motoneuron pools (MNP) of the posterior iliotibial and femorotibial muscles were located at the dorsolateral part of the lateral motor column of the lumbosacral spinal segments (LS) 1-4 and 1-3, respectively. Although dendritic extensions of femorotibial MNP was fewer and shorter than that of the posterior iliotibial MNP, distribution pattern of dendrites of these two MNPs were quite similar. Dendritic profiles were equally distributed in the white and gray matters. The MNP of posterior iliotibial muscle have dendrites extending all the directions. A large number of dendrites penetrated in the white matter, and many of them reached to the pial surface of the lateral and ventral funiculi, Dendrites directing to the dorsomedialwards reached to the base of the dorsal horn. MNPs of both the iliofibular (LS4-7) and caudilioflexorius (LS6-8) had dendritic trees, which extended along both lateral and ventral border of the lateral motor column. From these observation we concluded that there are major differences in the distribution of dendrites of MNPs innervating different hind limb muscles of the chicken.