Preparation and characterization of single cells from the avian salt gland

In preparation for pulse-chase autoradiography experiments and studies of cell surface changes of relevance to plasma membrane biogenesis, we have prepared a cell suspension from the salt gland of ducklings. The method used was a modification of previous methods used for pancreas and salivary gland and included digestions with collagenase and hyaluronidase, divalent cation chelation, and dispersion by gentle pipetting. Yields were 1.13 X 10(7) cells/g gland, and cell recovery was 45% by DNA assay. Recovery of Na,K-ATPase, a marker for salt gland secretory cells was 40--47%. Cell viability was strongly indicated by trypan blue exclusion and 3H-leucine incorporation. Transmission and scanning electron microscopy revealed that most cells retained ultrastructural features characteristic of the intact gland. Smaller cells (3--8 micrometers in diameter), exhibiting few surface microvilli and relatively few cytoplasmic organelles, likely represented the undifferentiated, peripheral cells from the tips of secretory tubules. Larger cells (5--10 micrometers in diameter), exhibiting prominent surface membrane folds enclosing numerous mitochondria, likely represented the functional, secretory cells of the salt gland tubules in various stages of differentiation. The surface folds presented as microvilli and microplicae in scanning electron micrographs.