title: Light- and electron-microscopic study of substance P-immunoreactive neurons in the guinea pig retina.
abstract: Substance P (SP) immunoreactivity in the guinea pig retina was studied by light and electron microscopy. The morphology and distribution of SP-immunoreactive neurons was defined by light microscopy. The SP-immunoreactive neurons formed one population of amacrine cells whose cell bodies were located in the proximal row of the inner nuclear layer. A single dendrite emerged from each soma and descended through the inner plexiform layer toward the ganglion cell layer. SP-immunoreactive processes ramified mainly in strata 4 and 5 of the inner plexiform layer. SP-immunoreactive amacrine cells were present at a higher density in the central region around the optic nerve head and at a lower density in the peripheral region of the retina. The synaptic connectivity of SP-immunoreactive amacrine cells was identified by electron microscopy. SP-labeled amacrine cell processes received synaptic inputs from other amacrine cell processes in all strata of the inner plexiform layer and from bipolar cell axon terminals in sublamina b of the same layer. The most frequent postsynaptic targets of SP-immunoreactive amacrine cells were the somata of ganglion cells and their dendrites in sublamina b of the inner plexiform layer. Amacrine cell processes were also postsynaptic to SP-immunoreactive neurons in this sublamina. No synaptic outputs onto the bipolar cells were observed.
authors.affiliation: Department of Anatomy, Catholic University Medical College, Seoul, Korea.
authors.forename: M Y
authors.initials: MY
authors.lastname: Lee
authors.forename: M H
authors.initials: MH
authors.lastname: Chun
authors.forename: S H
authors.initials: SH
authors.lastname: Han
authors.forename: S J
authors.initials: SJ
authors.lastname: Oh
authors.forename: J W
authors.initials: JW
authors.lastname: Chung
mesh_terms: D000818:Animals; D005260:Female; D006168:Guinea Pigs; D007124:Immunoenzyme Techniques; D008297:Male; D008853:Microscopy; D008854:Microscopy, Electron; D009474:Neurons / Q000378:metabolism / Q000648:ultrastructure*; D012160:Retina / Q000166:cytology* / Q000378:metabolism / Q000648:ultrastructure; D013373:Substance P / Q000378:metabolism*; D013569:Synapses / Q000378:metabolism / Q000648:ultrastructure
chemical_list: D013373:Substance P