ONSET AND DEVELOPMENT OF TRANSMISSION IN CHICK CILIARY GANGLION
ONSET AND DEVELOPMENT OF TRANSMISSION IN CHICK CILIARY GANGLION
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DOI：
10.1113/jphysiol.1972.sp009822
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发表时间：
1972-01-01
影响因子：
5.5
通讯作者：
PILAR, G
中科院分区：
文献类型：
--
作者：
LANDMESSER, L;PILAR, G
1.从第25阶段（Hamburger &汉密尔顿，1951）到孵化后28天，在离体鸡睫状神经节中对传输的开始和发展进行了电生理学研究。同时观察突触的超微结构.突触传递在第26½阶段开始，到第33阶段，在睫状体和脉络膜两个细胞组中均为100%。它最初是化学的，直到第41阶段，当有效的电耦合首次出现在睫状体中。电传递突触的比例在孵化后1 - 2天增加到80%。在第33½阶段，当所有神经节细胞都在传递信号时，几乎没有形态学突触。突触小泡的稀缺性持续到胚胎发育后期，此时所有的睫状细胞都具有花萼。孵化时，肾盏内充满突触囊泡.最初的突触接触是通过精细的终末分支，通常位于早期神经节细胞的复杂突起上。从第36½期开始形成睫状体，并伴随着神经节细胞突起的收缩，因此到第40期，所有睫状细胞都有简单的睫状体。花萼是一个过渡性的结构，从孵化后的第一周开始分裂成一簇钮扣。5.化学突触后电位（PSP）处于第40阶段（30 ×膜时间常数），并通过艾司氯胺酮进一步延长。到第43阶段，PSP已变得明显缩短，不受Esplatin的影响。不能简单地解释发育过程中PSP时程和对抗胆碱酯酶敏感性的变化。来自第40期睫状细胞的细胞内记录显示1 - 2 mV振幅、双相、快速衰减的电耦合电位（CP），睫状细胞均具有肾盏。在发育后期，CP的振幅变为20-40 mV，衰减更慢，呈双相。这似乎与更快的突触前传导速度和细胞索马的髓鞘形成有关。CP的这种变化可能反映了从电容性耦合到电阻性耦合的转变，并指出了几个因素在不同程度上影响了电传输。支配睫状细胞的突触前纤维从较低的阈值和较快的传导速度比支配睫状细胞，发生在成人。结论是，这些节前纤维可能是指定的时间传输开始，他们选择性地支配适当的突触后细胞。
1. The onset and development of transmission has been studied electro‐physiologically in the isolated chick ciliary ganglion from Stage 25 (Hamburger & Hamilton, 1951) until 28 days after hatching. Ultrastructure of the synapses was concomitantly investigated.2. Synaptic transmission began at Stage 26½ and was 100% in both cell groups, ciliary and choroid, by Stage 33. It was initially chemical until Stage 41 when effective electrical coupling first appeared in the ciliary population. The proportion of electrically transmitting synapses increased to 80% by 1‐2 days post‐hatching.3. Few morphological synapses were present at Stage 33½ when all ganglion cells were transmitting. A scarcity of synaptic vesicles persisted until late in embryonic development when all ciliary cells possessed calyces. At hatching the calyces were filled with synaptic vesicles.4. Initial synaptic contacts were by fine terminal branches often on the intricate processes of early ganglion cells. Calyces formed from Stage 36½ and there was a concomitant retraction of ganglion cell processes, so that by Stage 40 all ciliary cells had simple calyces. The calyx was a transitory structure, which from the first week post‐hatching began to break up into a cluster of boutons.5. Chemical post‐synaptic potentials (PSPs) were at Stage 40 long (30 × the membrane time constant) and further prolonged by eserine. By Stage 43, PSPs had become markedly shortened and were unaffected by eserine. No simple explanation can be offered for the changes in PSP time course and sensitivity to anticholinesterases during development.6. Intracellular records from Stage 40 ciliary cells, which all possess calyces, showed 1‐2 mV amplitude, diphasic, fast decaying electrical coupling potentials (CPs). Later in development the CPs became 20–40 mV amplitude, more slowly decaying and monophasic. This seemed to be correlated with faster presynaptic conduction velocities and myelination of the cell soma. Such changes in CPs may reflect a shift from capacitative to more resistive coupling and point to several factors contributing in varying degrees to the electrical transmission.7. Presynaptic fibres innervating ciliary cells were from the start of lower threshold and faster conduction velocity than those innervating ciliary cells, as occurred in the adult. It is concluded that these preganglionic fibres were probably specified by the time transmission starts and that they selectively innervated the proper post‐synaptic cells.