d bandwidth of emission from OH and H/sub 2/O maser spheres that are expanding or contracting and that are homogeneously or inhomogenously pumped. Amplification of resonant acatter is shown to be less important than that of spontaneous emission in detemnining the small apparent interferometer sizes of emitters. The actual sizes are possibly 10-100 times the apparent ones (for sources near the compact H II regions). Appreciable saturation line broadening is calculated for partially or fully saturated spherers, in centradiction to the results of Peters and Allen. (auth)