• The Korean Journal of Zoology
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• v.35 no.4
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• pp.428-438
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• 1992

The serotonin-immunoreactive (5-HTil neurons have been investigated in the brains of lanra, pupa and adult from Pieris ropae. There are ca. 54 5-HTi neurons in 5-instar larva, ca. 20 in 2-dav-old pupa and ca. 118 in 1-day-old adult, respectively. Most of these 5-HTi neurons are interneurons, but efferent and afferent 5-HTi neurons were also observed. Most of the 5-HTi neurons project into the central neuropils of postembrvonic brains. The larval brain contains abundant 5-HTi processes in the central neuropils, including those in three cerebral commissures. But in the pupal brain the 5-HTi processes are restricted in small numbers to the given regions of central neuropil. The adult brain contains a large number of 5-HTi processes in mushroom body, central body complex, lateral protocerebrum, protocerebral bridge, antennal lobe, and tritocerebral and suboesophageal neuropils. However, the 5-HTi processes are not found in the optic lobe of the brains. One prominent feature of the 5-HTi fibers in the postembrvonic brains is the fact that they are greatly arborized.