The ultrastructural localization of Tamm-Horsfall protein (THP) was studied in paraformaldehyde-fixed human renal biopsies. Pre-embedding and post-embedding immunogold labelling techniques were developed utilizing a monoclonal antibody specific for human urinary THP. With the pre-embedding technique, membrane contrast was enhanced by osmification thus allowing precise localization of gold particles. Reasonable tissue penetration of antibodies was achieved without compromising ultrastructural detail. The hydrophilic resin LR White was used for post-embedding labelling to ensure maximum penetration of antibodies. However, sections had only mild osmification and consequently localization of label was less certain. Both labelling techniques gave similar results. THP was found to be associated with two renal cell types. Epithelial cells lining the thick ascending limb of Henle's loop had gold label closely associated with the whole cell plasmalemma, with some of these cells having an apparently random distribution of label throughout the cytoplasm. Only the luminal plasmalemma of epithelial cells lining distal convoluted tubules were found to be labelled. Basolateral membranes and the cytoplasm of these cells were negative. The use of a monoclonal antibody of defined specificity combined with the two immunolabelling procedures represents a precise reliable method for studying ultrastructural localization of THP in the human kidney.
Histochemical and ultrastructural studies of primary sensory neurons in mice with dystonia musculorum. I. Acetylcholinesterase and lysosomal hydrolases
Enzyme histochemical and fine structural studies were performed on mice with a hereditary sensory neuropathy (dystonia musculorum). The dystonic mice were compared with normal litter mates. Acetylcholinesterase activity was studied in trigeminal and spinal ganglia and sensory receptors as well as in sympathetic ganglia. Lysosomal hydrolases and ultrastructural features were studied in the trigeminal and spinal ganglia. Striking changes in the amount and distribution of enzymic activity were observed in the perikarya of sensory ganglion neurons in dystonic mice. Perikaryal involvement was indicated by displacement of the nucleus, enlargement of the perikaryon, peripheral location of Nissl substance, loss of enzymic activity and an increase in the number of neurofilaments–features similar to those that follow physical interruption of the axon. The focal axonal swellings that occurred along sensory nerve fibers contained concentrations of lysosomal hydrolases and sometimes acetylcholinesterase activity. They were generally more numerous in the nerve fibers located distal to the ganglion rather than proximal to it. At the ultrastructural level these swellings contained lysosomal bodies and remnants of organelles. Some abnormalities in the myelin and the size of paranodal gaps were also observed. These results are discussed in relation to interruptions in axoplasmic flow and experimental neuropathies including those of the ‘dying‐back’ type.
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