title: Ultrastructural identification of entorhinal cortical synapses in CA1 stratum lacunosum-moleculare of the rat.
abstract: The goal of the present study was to identify and characterize, at the electron microscopic level, the synapses formed by entorhinal cortical (EC) axons in the hippocampal CA1 stratum lacunosum-moleculare of the adult rat. Phaseolus vulgaris leucoagglutinin was ionotophoresed at various loci throughout the mediolateral and dorsoventral extent of the EC to label EC-CA1 synapses. Virtually all labeled synapses were asymmetric and axospinous. EC axons did not preferentially synapse with any particular type of dendritic spine; rather, EC axons formed synapses with the range of dendritic spine morphologies observed in CA1 s. lacunosum-moleculare. Spines with either perforated or nonperforated postsynaptic densities were contacted by EC axons. Occasionally both a labeled and an unlabeled axon synapsed on a single dendritic spine head. The data are discussed in relation to the morphology of other afferent systems synapsing in s. lacunosum-moleculare and to the physiology of the EC-CA1 system.
authors.affiliation: Department of Neurological Surgery, University of Virginia Health Sciences Center, Charlottesville 22908.
authors.forename: N L
authors.initials: NL
authors.lastname: Desmond
authors.forename: C A
authors.initials: CA
authors.lastname: Scott
authors.forename: J A
authors.initials: JA
authors.lastname: Jane
authors.forename: W B
authors.initials: WB
authors.lastname: Levy
mesh_terms: D000818:Animals; D001370:Axonal Transport; D001369:Axons / Q000648:ultrastructure; D003712:Dendrites / Q000648:ultrastructure; D018728:Entorhinal Cortex / Q000648:ultrastructure*; D006624:Hippocampus / Q000648:ultrastructure*; D008297:Male; D009434:Neural Pathways / Q000648:ultrastructure; D010835:Phytohemagglutinins; D051381:Rats; D017207:Rats, Sprague-Dawley; D013569:Synapses / Q000648:ultrastructure*
chemical_list: D010835:Phytohemagglutinins; C100156:leukoagglutinins, plants