ULTRASTRUCTURE OF THE GILL EPITHELIA IN THE CRAYFISH PROCAMBARUS-CLARKII AT DIFFERENT STAGES OF THE MOLT CYCLE

The ultrastructure of gill filament epithelia of the crayfish Procambarus clarkii was examined during all stages of the molt cycle. When compared to events in the telson, apolysis and preexuvial cuticle deposition were greatly delayed in both respiratory and ion-transporting gill filament types, occurring only during the last 10% of the premolt. No postexuvial cuticular deposition was noted, the cuticle appearing to be complete immediately after ecdysis. No changes in the morphology of gill filament epithelia were noted that would indicate epithelial involvement in preexuvial cuticle synthesis. Silver staining, used to detect epithelia involved in active transport of ions, revealed staining patterns during all stages of pre- and postmolt that were similar to patterns seen in intermolt animals.