Abstract
Lead oxalacetate, a primary reaction product precipitate for the visualization of the activity of glutamic oxalacetic transaminase in tissue sections, is stable at a slightly alkaline pH. At concentrations which are used for tissue fixation a slight inhibitory effect on glutamic oxalacetic transaminase activity is produced by acetone while a glutaraldehyde-formaldehyde mixture results in marked reduction of activity. The concentration of lead which is used to form the primary reaction product does not significantly inhibit this enzyme activity.