title: Serotonin and opsin immunoreactivities in the developing pineal organ of the three-spined stickleback, Gasterosteus aculeatus L.
abstract: 5-hydroxytryptamine (5-HT, serotonin)- and opsin-immunoreactive sites were studied in the developing pineal complex of the stickleback, Gasterosteus aculeatus L., by use of light-microscopic indirect immunoperoxidase techniques. 5-HT immunoreactivity first occurs in the pineal organ at the age of 80 h after fertilization and appears to be localized in cells of the photoreceptor type. The outer segments of a few pineal photosensory cells exhibit opsin immunoreactivity at the age of 84 h after fertilization. The number of cells seems to increase until the pineal organ is completely developed. The increase in the number of 5-HT immunoreactive perikarya runs parallel in time to that of the opsin-immunoreactive outer segments. The cells of the parapineal organ show neither opsin nor 5-HT immunoreactivity. The retina of the embryonic stickleback does not display opsin immunoreactivity until after hatching, which takes place about 144 h after fertilization. These results suggest, in the three-spined stickleback, an earlier light-perception capacity for the developing pineal organ than for the retina.
mesh_terms: D000818:Animals; D004625:Embryo, Nonmammalian / Q000502:physiology; D005136:Eye Proteins / Q000032:analysis*; D005260:Female; D005306:Fertilization; D005399:Fishes; D007124:Immunoenzyme Techniques; D010786:Photoreceptor Cells / Q000166:cytology; D010870:Pineal Gland / Q000196:embryology / Q000254:growth & development*; D012168:Retinal Pigments / Q000032:analysis*; D017299:Rod Opsins; D012701:Serotonin / Q000032:analysis*
chemical_list: D005136:Eye Proteins; D012168:Retinal Pigments; D017299:Rod Opsins; D012701:Serotonin