Changes in granular endoplasmic reticulum induced in cultured human monocytes by colony stimulating factor

The supernatant portion of cultured human monocytes produces a biological factor known as colony stimulating factor. The addition of culture fluid containing colony stimulating factor to cultured human monocytes produced morphologic changes in the granular endoplasmic reticulum. Granular endoplasmic reticulum changed its appearance from long slender cisternae to a concentric pattern (whorls) averaging seven rows per structure 120 min following the addition of culture fluids containing colony stimulating factor.