Where does “endoscheletro” come from?

endoscheletro (Italian) comes from Italian endo-, from Ancient Greek ἔνδον, from Proto-Hellenic éndon, from Proto-Indo-European h₁n̥dóm, from Proto-Indo-European h₁n̥dó, from Proto-Indo-European h₁én — in.

endoscheletro (Italian): endoskeleton