Original image in Valverde de Amusco, Juan, c. 1525-c. 1588. Historia de la composicion del cuerpo humano. Engraving attributed to Nicolas Beatrizet from a drawing by Gaspar Becerra.

Vesalius' Fabrica ignited criticism. A former student of Vesalius, Matteo Realdo Colombo, took advantage of Vesalius' absence from the University of Padua after the publication of the Fabrica to advance his own career through criticism of Vesalius' work. Colombo included content from the Fabrica while at the same time telling his students that he, Colombo, could improve upon Vesalius' work.

Spaniard Juan Valverde de Amusco criticized Vesalius at the same time that he used many of Vesalius' prints in his own anatomical books, De animi et corporis sanitae tuenda libellus, published in 1552, and Historia de la composición del cuerpo humano, published in 1556. Both books include smaller copies and edited versions of Vesalius' illustrations, although many of them appear distorted or inaccurate because of the printing quality. The few original illustrations in Valverde's books are bizarre, like the fragmented torsos clothed in Roman military garb and the famous flayed man who holds a dagger and his own skin.

Criticism of the Fabrica focused on four main points: 1) Vesalius' theories were not that radical. While Galen's dissections were done mostly on animals, he did conduct some human dissections. Vesalius simply expanded upon Galen; 2) Vesalius was led astray by misunderstandings and errors within the translations of Galen's Greek; 3) Renaissance bodies were different from Roman bodies, which resulted in the “errors” corrected by Vesalius, and 4) perhaps Vesalius was simply wrong.

These conflicts and criticisms led to a shift in the study of anatomy, ushering in an era in which the authority of established texts was superseded by experimentation, comparison, and the experience of the senses.