Instrumentation in the Missa Papae Marcelli?

The Missa Papae Marcelli, composed by Giovanni Pierluigi da Palestrina, is primarily written for a six-part choir (SSATBB) without instrumental accompaniment, emphasizing the purity of vocal harmony. This choral work showcases Palestrina's mastery of counterpoint and text setting, allowing the sacred text to be clearly understood through the music. While it is often performed a cappella, instrumental support can be added for modern performances, typically using strings or a small organ, to enhance the overall sound while maintaining the work's original choral integrity.