Subcellular localization of calcium in the coronet cells and tanycytes of the saccus vasculosus of the rainbow trout, Salmo gairdneri Richardson.

The intracellular localization of calcium in the saccus vasculosus of the rainbow trout, Salmo gairdneri Richardson, was studied by means of ultracytochemical and X-ray microanalytical techniques. Using a variant of the glutaraldehyde/potassium pyroantimonate-osmium tetroxide method, Ca was detected in mitochondria, smooth endoplasmic reticulum and primary vesicles of coronet cells, and in mitochondria and smooth endoplasmic reticulum of tanycytes. Mitochondria and smooth endoplasmic reticulum in both cell types are considered as general Ca-stores. The primary vesicles in the ciliary globules of coronet cells are viewed as additional Ca-reservoirs. Possible roles of these Ca-stores in the regulation of transport activities of coronet cells in the homeostasis of the CSF are discussed.