title: Horseradish peroxidase evidence for a spinal projection from the preoptic area of the goldfish, a light and electron microscopic study.
abstract: Horseradish peroxidase (HRP) was applied to the transected spinal cord of goldfish labeled neurons in the preoptic area. Since leakage of HRP into the blood could produce the labeling of neurosecretory cells, intraperitoneal (i.p.) injections of HRP were made with a wide range of dosages in order to intentionally label preoptic neurosecretory cells. The distribution of preoptic neurons labeled after spinal HRP application was far more restricted than the labeling via uptake of HRP from the blood, even when cells in the spinal cord-transected fish were intensely labeled. Furthermore, in HRP electron microscopic material, morphological differences were observed between neurons labeled by the two procedures. Large numbers of dense core vesicles and well-developed stacks of rough endoplasmic reticulum, features typical of cells projecting to the pituitary, were not observed in cells labeled via the spinal cord. These findings indicate that in goldfish a direct projection exists from the preoptic area to the spinal cord which could be homologous to one arising from the paraventricular nucleus of mammals. Both i.p. injection and spinal transection also produced labeling of more caudal periventricular diencephalic cells which resemble preoptic cells in efferent projections as well as ultrastructural features.
mesh_terms: D000818:Animals; D003530:Cyprinidae / Q000254:growth & development*; D006054:Goldfish / Q000254:growth & development* / Q000502:physiology; D006735:Horseradish Peroxidase; D008854:Microscopy, Electron; D009474:Neurons / Q000502:physiology / Q000648:ultrastructure; D009490:Neurosecretory Systems / Q000166:cytology; D010544:Peroxidases; D011301:Preoptic Area / Q000166:cytology / Q000502:physiology* / Q000648:ultrastructure; D013116:Spinal Cord / Q000166:cytology / Q000502:physiology* / Q000648:ultrastructure; D009435:Synaptic Transmission
chemical_list: D006735:Horseradish Peroxidase; D010544:Peroxidases