MORPHOLOGICAL IDENTIFICATION OF LIVE GONADOTROPIN, GROWTH-HORMONE, AND PROLACTIN CELLS IN GOLDFISH (CARASSIUS-AURATUS) PITUITARY-CELL CULTURES

To better understand neuroendocrine regulation and the intracellular mechanisms mediating pituitary-hormone release, it is necessary to study the physiology of identified single cells. We have developed a system to identify gonadotropin, growth-hormone, and prolactin cells in primary cultures of goldfish pituitary cells. Using Nomarski differential interference-contrast microscopy, the unique morphologies of discrete subpopulations of cells were characterized. To aid in the initial characterization of different pituitary-cell types, a discontinuous Percoll density-gradient cell-separation technique was developed. This method provided fractions enriched with functional gonadotropin, growth-hormone, and prolactin cells. The morphology of each cell type was initially characterized in enriched fractions of immunofluorescently labelled cells using differential interference-contrast microscopy. The cell type-specific morphologies were then confirmed in live pituitary-cell cultures. Gonadotropin, growth-hormone, and prolactin cells were correctly identified in live mixed cultures in 92, 94, and 100% of the trials, respectively. The ability to directly identify cells in primary cultures allows the physiological study of identified single cells with minimal pretreatment.