'Palestrina’s masses run the gamut of styles from the consistently contrapuntal Missa ad fugam, through the largely homophonic but texturally varied Missa Papae Marcelli, designed for word-intelligibility (see Jeppesen’s statistical comparison of its Gloria and Credo sections with those of other masses, 1923), to the antiphonal dialogue of the four polychoral masses.'
From 'Grove Music Online'