Fine structure of the ocellus of the hydromedusan, Spirocodon saltatrix. I. Receptor cells.

摘要: The fine structure of the ocellus hydromedusan, Spirocodon saltatrix, has been examined. is situated on dorsum each tentacular base. Each appears to be an invagination a thickened ectodermal layer called eyecup. eyecup formed by palisade-like arrangement nonpigmented receptor processes and pigmented supporting cells. process bears single cilium which 9+2 tubular pattern. projects into lumen eyecup, where it enlarges, its membrane becomes wavy. cell contains pigment granules many microvilli within lumen. Cell bodies cells lie under processes. axon, microtubules, mitochondria, vesicles relatively uniform size (80–110 nm). axons terminate at base or periphery they intertwine with second-order neurons. neurons are varied shape, their located in surrounding ocellar retina contain various (up 200 nm) form. Since there no glial elements ocellus, neighboring usually juxtaposed, separated from one another only irregular intercellular space. However, plasma membranes nervous gap presumed synaptic loci. Synapses occur between (cell body axon) (dendrite, axon). Two types synapses present; afferent synapse element presynaptic feedback also presynaptic. Afferent more frequently than synapses.