Muscles on the Fly

What am I looking at?  

This is a cross section of the flight muscles that move the wings of a dancer damselfly. Each muscle is made up of many individual fibers packed tightly together. These units are made of filamentous actin-rich fibers called myofibrils (shown in blue, 1), which surround a core of nuclei (in yellow, 2). In between the fibers are dark areas containing the mitochondria that power up the muscles (3). You can also see the axons of motor neurons (in red, 4), which stimulate the muscle fibers.

Click on the right arrow to see a slightly different view of these structures.

Biology in the background  

The blue-fronted dancer damselfly is found around ponds and other bodies of water. The insect’s flight apparatus consists of two pairs of wings, each powered by eight muscles. In dragonflies and damselflies, their flight muscles are attached directly to their wings, meaning they use a direct flight mechanism – unlike all other flying insects, which have an indirect flight mechanism whereby their flight muscles aren’t attached directly to their wings.

But unlike dragonflies, damselflies hold their wings parallel to their slender body at rest and don’t fly as fast. Dancers’ flight patterns are particularly unique and not straight-lined like those of their relatives. They appear to flutter, bounce, and dance through the air – hence their name.

The width of each of these muscle cells is about 2 micrometers, or roughly 35 times smaller than the width of a human hair.

Technique  

This image was created using confocal microscopy.