Westfall Jane A, Elliott Carol F, Carlin Ryan W
Department of Anatomy and Physiology, Kansas State University, Manhattan, Kansas 66506-5602, USA.
J Morphol. 2002 Jan;251(1):83-92. doi: 10.1002/jmor.1075.
Sensory and ganglion cells in the tentacle epidermis of the sea anemone Aiptasia pallida were traced in serial transmission electron micrographs to their synaptic contacts on other cells. Sensory cell synapses were found on spirocytes, muscle cells, and ganglion cells. Ganglion cells, in turn, synapsed on sensory cells, spirocytes, muscle cells, and other neurons and formed en passant axo-axonal synapses. Axonal synapses on nematocytes and gland cells were not traced to their cells of origin, i.e., identified sensory or ganglion cells. Direct synaptic contacts of sensory cells with spirocytes and sensory cells with muscle cells suggest a local two-cell pathway for spirocyst discharge and muscle cell contraction, whereas interjection of a ganglion cell between the sensory and effector cells creates a local three-cell pathway. The network of ganglion cells and their processes allows for a through-conduction system that is interconnected by chemical synapses. Although the sea anemone nervous system is more complex than that of Hydra, it has similar two-cell and three-cell effector pathways that may function in local responses to tentacle contact with food.
在一系列透射电子显微镜图像中追踪了苍白艾氏海葵触手表皮中的感觉细胞和神经节细胞，直至它们与其他细胞的突触接触。在螺旋细胞、肌肉细胞和神经节细胞上发现了感觉细胞突触。反过来，神经节细胞在感觉细胞、螺旋细胞、肌肉细胞和其他神经元上形成突触，并形成沿途轴-轴突触。未追踪到刺细胞和腺细胞上的轴突突触的起源细胞，即已鉴定的感觉细胞或神经节细胞。感觉细胞与螺旋细胞以及感觉细胞与肌肉细胞之间的直接突触接触表明，存在一条用于螺旋囊放电和肌肉细胞收缩的局部双细胞通路，而在感觉细胞和效应细胞之间插入一个神经节细胞则形成了一条局部三细胞通路。神经节细胞及其突起的网络形成了一个通过化学突触相互连接的传导系统。虽然海葵的神经系统比水螅的更复杂，但它具有类似的双细胞和三细胞效应通路，可能在触手接触食物的局部反应中起作用。
