Did Michelangelo include a hidden caricature of himself in one of his famous sketches?

A new Clinical Anatomy article presents evidence that Michelangelo inserted his self-portrait into a sketch of his close friend, Vittoria Colonna, which is currently in the collection of the British Museum in London, England. This self-caricature of Michelangelo may serve as a tool for analysing the artist's probable bodily dimensions and even his state of health at the time.

In the portrait of Michelangelo's friend, a small figure can be seen standing in the area immediately in front of her abdomen and between the lines that form part of her dress. The caricature is leaning forward at an acute angle, as if he himself were drawing the portrait.

The caricature may have been a signature of sorts, according to lead author Dr. Deivis de Campos, of the Federal University of Health Sciences of Porto Alegre, in Brazil. During Michelangelo's time, there were many restrictions on artists and their work, perhaps the main one being that artists were not allowed to sign their works.