Histochemistry of acetylcholine receptors and acetylcholinesterase during the formation of neuromuscular junctions in the urodele Hynobius nigrescens

✍ Scribed by Masahiro Tabuchi; Keiko Fujikura; Sakae Inoue

• Publisher: John Wiley and Sons
• Year: 1991
• Tongue: English
• Weight: 653 KB
• Volume: 207
• Category: Article
• ISSN: 0362-2525
• DOI: 10.1002/jmor.1052070102

✦ Synopsis

The development and structure of neuromuscular junctions (n-m-js) in stylopodia of forelimbs of larvae and adults of Hynobius nigrescens were histochemically investigated for acetylcholine receptors (AChRs) and acetylcholinesterase (AChE) activity. In larvae, the tetramethyl rhodamine-labelled α-bungarotoxin (TMR-αBT) positive areas appeared either as small fluorescent spots or fluorescent plates of various sizes. The mature fluorescent plate was found to be formed by the successive addition of spots, and the plates thus established were arranged linearly parallel to the axes of muscle fibers. AChE activity occurred almost exactly at TMR-αBT-positive sites. In adults, plate assemblies were often seen as a single dotted line (type A form) for both AChR binding and AChE reaction, in contrast to larval n-m-js in which AChE activity appeared as a continuous line. By applying the TMR-αBT method, two other forms of adult n-m-js were observed: type B, a long dotted line several plates wide; and type C, with a cluster of plates randomly dispersed over the whole width of the muscle fiber. It seems that protoforms of the latter two forms of n-m-js appear in the muscles just before and after metamorphosis.