Mono- and oligo-vesicular synapses and their connectivity in a Cnidarian sensory epithelium (Coryne tubulosa)
Mono- and oligo-vesicular synapses and their connectivity in a Cnidarian sensory epithelium (Coryne tubulosa)
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DOI：
10.1002/cne.1118
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发表时间：
2001-04-16
影响因子：
2.5
通讯作者：
Thurm, U
中科院分区：
文献类型：
--
作者：
Holtmann, M;Thurm, U
球形端球的触角的头状水螅是一个进化早期的范例的化学和mechanosensory上皮细胞组成的四种类型的感觉细胞和一种类型的chemo-mechanosensitive acidocytes（刺细胞），所有分离的支持细胞。上皮细胞辨别刺激的部位和成分，并诱导各种行为。最近的电生理研究表明，快速的化学突触信号传输的毛细胞和mechanosensory毛细胞，在幅度和持续时间分级。目前的电子显微镜工作，应用连续切片，分析的信号传输和传出控制的触角球Coryne tubulosa，一个物种也在以前的研究中使用的超微结构基础。感觉细胞和近端神经节细胞的神经突在外胚层细胞的基部构成神经丛。没有神经节细胞位于球体内。通常构型的化学突触连接神经突或传出到毛细胞和毛细胞。这些突触中的每一个仅包含3-10个直径为70-150 nm的透明和/或致密核心囊泡（寡囊泡突触）。对于毛细胞和毛细胞的分级传入信号传递，唯一的候选者是在这些细胞的基部定期发生的神经突接触区。在它们的突触前侧，大多数是一个（很少有两到四个）大囊泡（160-1100 nm直径的大囊泡）附着在表面膜密度。为了调和结构和功能的数据，一个短暂的融合和部分耗尽的固定囊泡被认为是单囊泡突触中释放的递质，类似于最近的研究结果，脊椎动物内分泌。同样的原则进行了讨论，通常寡泡突触的刺胞动物。(C)2001 Wiley-Liss，Inc.
The spherical end-knobs of the tentacles of capitate hydropolyps are an evolutionarily early paradigm of a chemo- and mechanosensory epithelium composed of four types of sensory cells and one type of chemo-mechanosensitive nematocytes (stinging cells), all separated by supporting cells. The epithelium discriminates sites and compositions of stimuli and induces various kinds of behavior. Recent electrophysiological studies demonstrated rapid chemo-synaptic signal transmission of nematocytes and mechanosensory hair cells, graded in amplitude and duration. The present electron microscopic work, applying serial sectioning, analyses the ultrastructural basis of signal transmission and efference control in the tentacular spheres of Coryne tubulosa, a species also used in preceding studies. Neurites of sensory cells and of proximal ganglion cells constitute a nerve plexus at the base of the ectodermal cells. No ganglion cells are located within the spheres. Chemical synapses of the usual configuration connect neurites or are efferent to nematocytes and hair cells. Each of these synapses contains only 3-10 clear and/or dense-core vesicles of 70-150 nm diameter (oligo-vesicular synapses). For the graded afferent signal transmission of nematocytes and hair cells, the only candidates are regularly occurring zones of neurite contacts at the base of these cells. At their presynaptic side, mostly one (more seldom two to four) large vesicles (160-1100-nm-diameter magno-vesicles) are attached to a surface membrane density. In order to reconcile structural and functional data, a transient fusion and partial depletion of stationary vesicles is considered for the release of transmitter in mono-vesicular synapses, similar to recent findings for vertebrate endocrine secretion. The same principle is discussed for the usual oligo-vesicular synapses of Cnidaria. (C) 2001 Wiley-Liss, Inc.