Further investigations on the structure and function of the saccus vasculosus of the rainbow trout, Salmo gairdneri Richardson. Ultrastructural cytochemistry of membrane-bound alkaline phosphatase.

Alkaline phosphatase activity in coronet cells of the saccus vasculosus of the rainbow trout was localized ultracytochemically. Deposits of reaction product were found in varying amounts on the membranes of primary vesicles in the globules. This observation is discussed in relation to other morphological data and the possible resorptive function of the coronet cells in the homeostasis of the CSF.