Terminal Innervation Pattern in Striated Muscle of the Oyster Toadfish, Opsanus tau

Abstract

Striated muscle fibers from the body and head muscles of the oyster toadfishOpsanus tau, have been examined with particular attention to the innervation pattern and the characteristic shape and arrangement of the fibrils in the red and white muscle fibers. Methylene blue perfusion, gold chloride toning and cholinesterase localization were used to stain peripheral nerves and their endings. Both preterminal nerve fibers and motor endings show (AChE) activity. Red and white muscle fibers have multiple filamentous junctions throughout their length. The morphology and distribution of the motor endings on white muscle fibers is more diversified than on red fibers. The nerve terminals on white muscles appear as clusters of droplets while on red muscle fibers they appear as finger-like extensions of verrucosities. The innervation of red muscle is more dense than white muscle. Both red and white muscle fibers are polyinervated. Following fixation in gluteraldehyde and osmium tetroxide, transverse sections stained with a mixture of equal parts of 0.5% toluidine blue and 0.5% azure B show two types of fibrillar arrangement. The white muscle fibers show a single layer of ribbon-like fibrils around the periphery of the fiber and many polygonal fibrils in the center of the fiber. Nearly all of the fibrils in toadfish red muscle are larger and more irregularly disposed than in white muscle. The red muscle cells also contain more sarcoplasm than the white fibers.