Fine structure of the myocommata-muscle fibre junction in hoki (Macruronus novaezelandiae)

Transmission electron microscopic observations have been made of the interface between muscle fibres and myocommata of the fish, hoki (Macruronus novaezelandiae Hector). The fine structure of the interface is similar to that recorded for other vertebrate muscle. Collagen fibres from the myocommata penetrate sarcolemma‐lined invaginations into the base of the muscle fibre. A distinct basal lamina separates the sarcolemma from the collagen fibres. Microfilaments connect sarcolemma, basal lamina and collagen fibres. The myofibrils of the muscle fibre are connected to the inner sarcolemma surface by fine filaments from the final Z disc. During rigor mortis the structure of the interface remains unchanged. During post‐rigor storage on ice there is progressive breakdown at the interface, particularly of the invaginating collagen fibres and the basal lamina, resulting in detachment of muscle fibres from the myocomma.