Cytoskeletal proteins in cultured secretory cells from rat pituitary

Cultured cells from female rat pituitaries were examined by immunofluorescence microscopy for the presence of pituitary hormones and for cytoskeletal proteins. The cells attach well to glass coverslips and, when well-dispersed initially, develop networks of branching processes. Their cytoplasm appears granular and shows granular fluorescence when the cells are permeabilized and treated with antisera to pituitary hormones. The cultures contain fibroblasts which are morphologically distinct and much larger than the secretory cells. Consequently, they provide an internal control for cytoskeletal proteins in nonsecretory cells. Fibroblasts have relatively prominent stress fibres. By contrast, the secretory cells have a diffuse cytoplasmic distribution of all cytoskeletal proteins investigated. One cell type, the gonadotrope, which secretes luteinizing hormone and follicle-stimulating hormone, was examined in particular detail.