Do you not know that chaste women stay fresh much more than those who are not chaste? How much more in the case of the Virgin, who had never experienced the least lascivious desire that might change her body? 
Another explanation suggests that Michelangelo’s treatment of the subject was influenced by his passion for Dante’s Divina Commedia: so well-acquainted was he with the work that when he went to Bologna, he paid for hospitality by reciting verses from it. In Paradiso (cantica 33 of the poem), Saint Bernard, in a prayer for the Virgin Mary, says “Vergine madre, figlia del tuo figlio” (Virgin mother, daughter of your son). This is said because, since Christ is one of the three figures of Trinity, Mary would be his daughter, but it is also she who bore him.
A pietà (Italian pronunciation: [pjeˈta] ; meaning “pity”, “compassion”) is a subject in Christian art depicting the Virgin Mary cradling the dead body of Jesus, most often found in sculpture. As such, it is a particular form of the Lamentation of Christ, a scene from the Passion of Christ found in cycles of the Life of Christ. When Christ and the Virgin are surrounded by other figures from the New Testament, the subject is strictly called a lamentation in English, although pietà is often used for this as well, and is the normal term in Italian.
In a lesser known Michelangelo pietà, The Deposition, it is not the Virgin Mary who is holding Jesus’ body, but rather Nicodemus (or possibly Joseph of Arimathea), Mary Magdalene, and the Virgin Mary. There is some indication that the man in the hood is based on a self-portrait of the artist.  The sculpture is housed in the Museo dell’Opera del Duomo in Florence and is also known as the Florentine Pietà.
9. Among the most difficult damage to repair was Mary’s eyelid, which took approximately 20 tries before the restorers got it right.
3. Although he worked in Florence most of his life, Michelangelo sculpted the “Pieta” during a five-year period he spent in Rome. It was commissioned by Cardinal de Billheres.
In 1497, cardinal Jean Bilhères de Lagraulas commissioned Michelangelo to carve “a life-sized Virgin Mary, dressed, with a Dead Christ in her arms”.
The Pietà is defined as the depiction of the Virgin Mary holding the dying Christ in her arms. This was a popular scene in Northern European art of the late 15th century, and was a variation of the German wooden “Vesperbild”, that were mostly carved out of wood.
Since its 15th-century unveiling, the Pietà has had an eventful life. While, for centuries, it was housed in the cardinal’s Vatican City-based funerary chapel, it eventually found a permanent and prominent place in St. Peter’s Basilica, where it remains today.
Toward the end of the 15th century, young Florentine artist Michelangelo di Lodovico Buonarroti Simoni was already an esteemed artist. He was particularly renowned for his ability to paint and sculpt biblical figures with realistic anatomical features, culminating in commissions from Rome’s religious elite.