[Electron microscopic detection of ATPase activity in insect muscle after fixation with different fixatives]

The distribution of ATPase activity in the flight muscle of Locusta migratoria L. was studied at the fine structural level after a brief fixation in formaldehyde or in glutaraldehyde. In both the cases, the final product of reaction -- fine grained electron dense precipitation--was clearly revealed in intact contractile muscle structures. The glutaraldehyde fixation provides a good preservation of all the ultrastructural components of muscle cell, and reveals deposites of the final product in sarcomeres at the resting length. However, after the glutaraldehyde fixation it is very difficult to recognize regions of fibrillar reaction on electronmicroscopic preparation. The formaldehyde fixation does not provide a good preservation of membranous structures. However after the formaldehyde fixation reacting regions are more extensive than after glutaraldehyde fixation, and, moreover, it is possible to demonstrate a correlation between the activity and the contraction of sarcomere.