title: Ultrastructural evidence for the existence of the distal retinal pigment light-adapting hormone in the sinus gland of the prawn Palaemon paucidens.
abstract: The position of the distal retinal pigments was measured in the eyes of Palaemon which had been exposed to various light intensities (0-2000 lux) for periods up to 7 days. Electron microscopical observations of sinus glands from these animals revealed that long-term illumination (1000 lux, 7 days) resulted in almost complete degranulation of the Type 2 axon terminals, reflecting intense discharge of the granules. On the other hand, the Type 2 terminals of dark-adapted prawns showed no signs of hormone release, such as exocytosis. The results indicate that the light-adapting hormone is liberated from Type 2 terminals. The Type C cell somata in the medulla terminalis, containing granules of similar size to those in the Type 2 terminals, may be the site of synthesis of this hormone.
mesh_terms: D000818:Animals; D001369:Axons / Q000378:metabolism / Q000648:ultrastructure; D003594:Cytoplasmic Granules / Q000378:metabolism / Q000528:radiation effects / Q000648:ultrastructure; D004702:Endocrine Glands / Q000378:metabolism / Q000528:radiation effects / Q000648:ultrastructure; D005089:Exocytosis / Q000528:radiation effects; D005123:Eye / Q000648:ultrastructure; D005136:Eye Proteins / Q000378:metabolism*; D008027:Light; D008854:Microscopy, Electron; D033541:Palaemonidae / Q000033:anatomy & histology*; D012168:Retinal Pigments / Q000378:metabolism / Q000528:radiation effects
chemical_list: D005136:Eye Proteins; D012168:Retinal Pigments