Factors affecting the ultrastructural pattern of anterograde labeling in axon terminals with HRP.
Comparisons of anterograde labeling of axon terminals originating from short and long projection neurons were made in the hypoglossal nucleus. Injections of dilute and concentrated horseradish peroxidase (HRP) or wheat germ-agglutinin-horseradish peroxidase (WGA-HRP) were made via a glass micropipette into the nucleus reticularis parvocellularis (RPc = short projection neurons) and the Spinal V trigeminal complex (Sp. V = long projection neurons). Axon terminals in the hypoglossal nucleus, a common projection site of the two efferent systems, were evaluated ultrastructurally using diaminobenzidine (DAB) as the chromogen for the cobalt-glucose oxidase (CO-GOD) method of HRP labeling. Labeled axon terminals from these two sources demonstrated different distribution patterns of the reaction product. For the short pathway, high concentrations of the tracers resulted in diffuse, agranular labeling in the majority of axon terminals. Dilute concentrations of the tracers were associated with membrane-bound, granular type of labeling. All anterograde labeling of terminals of long projection neurons (Sp. V) was membrane-bound and granular irrespective of the tracer concentration. The length of the pathway and the concentration of the enzyme tracers are factors that affect the pattern of anterograde label in axon terminals of hypoglossal afferents.
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Borke
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Nau
D015100:3,3'-Diaminobenzidine; D000818:Animals; D001560:Benzidines; D002490:Central Nervous System / Q000033:anatomy & histology*; D002863:Chromogenic Compounds; D006735:Horseradish Peroxidase; D007002:Hypoglossal Nerve / Q000033:anatomy & histology; D009434:Neural Pathways / Q000033:anatomy & histology; D009445:Neuroanatomy / Q000379:methods*; D010544:Peroxidases; D051381:Rats; D012154:Reticular Formation / Q000033:anatomy & histology; D013194:Staining and Labeling; D014279:Trigeminal Nucleus, Spinal / Q000033:anatomy & histology
D001560:Benzidines; D002863:Chromogenic Compounds; D015100:3,3'-Diaminobenzidine; D006735:Horseradish Peroxidase; D010544:Peroxidases