“…dog or guinea pig), is capable of bone induction in adja cent muscles [2,4], There are reports of heterotopic bone formation occurring in humans; near ligated ureters [4], in the abdominal wall following suprapubic prostatecto my [5,6], and in the iliac muscles following autologous transplantation of urinary bladder mucosa [7], We are, however, very skeptical about the osteoinduc tive potential of the human urothelium. It appears that, in contrast with urothelium of dog, guinea pig, hamster, rab bit, and pig [8-14; for reviews, see 15,16], human urothe lium is devoid of osteoinductive potential [17,18]. Thus, humans belong, as mouse, cattle, and sheep, to species whose urothelium is devoid of osteoinductive potential [10,13,19], Our skepticism is based on the following:…”