Ultrastructure of photoreceptors and circadian pacemaker neurons in the eye of a gastropod,Bulla
Ultrastructure of photoreceptors and circadian pacemaker neurons in the eye of a gastropod,Bulla
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腹足动物 Bulla 眼中光感受器和昼夜节律起搏神经元的超微结构
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发表时间：
1983
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通讯作者：
W. Colquhoun
中科院分区：
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作者：
J. Jacklet;W. Colquhoun
海洋腹足动物头侧成对的每只眼睛直径约0.5毫米，包含约1000个大的光感受器、小的光感受器、大量的色素支持细胞和约130个神经元。光感受器有三种类型：大（90 μm × 20-30 μm）致密的光感受器（PRLD），具有精细的窄微绒毛和650个Å透明囊泡的聚集体；大透明细胞（PRLC）具有精细的宽微绒毛和650Å透明囊泡聚集；小而细长的受体（PRS），具有一簇微绒毛，缺乏囊泡聚集体。神经元（15-25 μm）含有1000个致密核Å囊泡，分布在视网膜周围或在感光层以下的神经膜周围聚集成一圈。最大的4-5个神经元位于颈圈区。神经元形态与电活动的相关性通过细胞内记录和路西法黄注射一些较大的神经元在衣领区，其动作电位有助于视神经冲动。每一个在视神经中都有一个轴突和通向神经节的突。它们是视神经记录的脉冲频率昼夜节律的起搏神经元，因为只有它们的动作电位与视神经脉冲呈1∶1的相关关系。光感受器与神经胶质细胞、光感受器与神经胶质细胞、神经突之间普遍存在间隙连接（具有五层结构），为视网膜细胞间的电紧张偶联提供了基础。视神经中约有2000个轴突（直径<3 μm），可能分别来自视网膜感光器和神经元以及来自大脑的传出纤维。在视神经鞘中可见副神经，包含几个大轴突。
SummaryEach of the paired cephalic eyes of the marine gastropod,Bulla, is about 0.5 mm in diameter and contains about 1000 large photoreceptors, small photoreceptors, numerous pigmented support cells and about 130 neurons. The photoreceptors are of three types: large (90 μm × 20–30 μm) dense ones (PRLD) with elaborate narrow microvilli and aggregates of 650 Å clear vesicles in the cytoplasm; large clear ones (PRLC) with elaborate wide microvilli and aggregates of 650Å clear vesicles; small slender receptors (PRS) with a tuft of microvilli and lacking vesicle aggregates. Neurons (15–25 μm) containing dense-core 1000 Å vesicles are in the periphery of the retina or grouped in a collar around the neuropil below the photoreceptor layer. The 4–5 largest neurons are in the collar area. Correlation of neuron morphology with electrical activity was done with intracellular recording and Lucifer yellow injection of some of the larger neurons in the collar area whose action potentials contribute to the optic nerve impulses. Each one has an axon in the optic nerve and processes that go to the neuropil. They are the pacemaker neurons of the circadian rhythm in impulse frequency that is recorded from the optic nerve, since only their action potentials are correlated 1 ∶ 1 with the optic nerve impulses. Gap junctions (with pentalaminar structure) are common between photoreceptors, glial cells, photoreceptors and glial cells, and neuronal processes in the neuropil, providing a basis for electrotonic coupling among retinal cells. There are about 2000 axons (diameter <3 μm) in the optic nerve, possibly one from each retinal photoreceptor and neuron plus efferent fibres from the brain. Accessory nerves, containing a few large axons, are seen in the optic nerve sheath.