The “petrified corpse”. The first study on the preservation status of skin

Paolo Gorini (1813-1881) was one of the first scientists who experiments “Petrification” of corpses, a particular technique used to obtain an artificial preservation of bodies that found wide application in Italy in the 19th century. This technique allowed to maintain the exact features of the deceased, preserve tissue, internal organs and hair in a state of stone hardness. This mechanism was based on the replacement of biological liquids with chemical preservatives obtained through intravascular injections. Paolo Gorini performed “Petrification” on hundreds of entire cadavers, or on parts of corpse, most of them housed in the “Collezione Anatomica Paolo Gorini” in Lodi. In this Museum, there is also the manuscript with the two formulas used by Gorini to petrified corpse: “a sulfuric acid solution in the proportion of ten percent or an alcohol-saturated solution of mercuric bichloride and muriate of calcium in the proportion that the volume of the first is ten times that of the second”. The aim of our work is to verify the preservation status of skin following “petrification” by Gorini. Our study was carried out on an entirely petrified body of an unknown individual held in the “Collezione Anatomica Paolo Gorini” in Lodi. The man was affected by a widespread bulbous-bullous manifestation, possibly smallpox or pellagra. A superficial fragment of skin, free of lesions, was biopsied from the latero-plantar region of the right foot. The analysis was performed using microscopic slides following the inclusion of the samples in epoxy resin , followed by a stain with hematoxylin-eosin and Masson's trichrome. Other sections were stained via immunohistochemical technique with anti-cytokeratin antibodies (AE1 AE3) and vimentin. The histological investigations revealed a discretely preserved epithelial tissue, with a structure that is still recognizable on the tangential sections. It’s possible to appreciate an easily detachable epithelium of the stratum corneum and deeper, more cohesive, layers (stratum granulosum and spinosum) in which the shadows of nuclei are still recognizable. Histochemical investigations revealed positivity for cytokeratins and negativity for vimentin. Differently from natural or embalmed mummified bodies, historic petrified specimens have never been analyzed. This first study demonstrates that the “Petrification” by Gorini guaranteed good skin preservation, maintaining its histological, histo-chemical, metachromatic and antigenic characteristics.