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KMID : 0381920020320020131
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Korean Journal of Microscopy
2002 Volume.32 No. 2 p.131 ~ p.147
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Fine Structure of Optic Lobes of Cephalopods (Todarodes pacificus and Octopus minor) inhabiting the Korean Waters
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Han Jong-Min
Chang Nam-Sub
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Abstract
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Optic lobes of Todarodes pacificus and Octopus minor are largely divided into cortex and medulla, the cortex being composed of three layers (an outer granule cell layer, a plexiform layer, and an inner granule cell layer). The cortex of Todarodes pacificus is about 420~450㎛ thick, being 170~200㎛ thicker than that of Octopus minor of which thickness is about 250~290㎛. In the outer granule cell layer of Todarodes pacificus, three types of nerve cells (type-A, type-B and type-C) and neuroglial cells that surround or contact with the neurons are observed, while in the outer granule cell layer of Octopus minor, two types of nerve cells (type-A and type-B) and a single type of neuroglial cells are observed. In a plexiform layer, a presynaptic bag and nerve endings are connected to each other, consequently forming various types of synaptosomes. The synaptosomes of Todarodes pacificus contain electron dense vesicles, electron dense-core vesicles and electron lucent vesicles, either individually or in a mixture. On the other hand, three types of synaptosomes a mixture of electron dense-core vesicles and electron lucent vesicles, electron lucent vesicles only, and electron dense-core vesicles only are observed in Octopus minor. The structures of the inner granule cell layer are almost similar in the two species. It is composed of two types of nerve cells (type-A, type-B) and a single type of neuroglial cells. In the medulla of Todarodes pacificus, the cells of 7×5㎛ are arranged to a line and form the palisade cell layer, but these are not observed in Octopus minor.
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KEYWORD
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Nerve cell , Neuroglial cell , Optic lobe , Synaptosome , Ultrastructure
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