The organ will come from a deceased donor, and the surgeons, from Johns Hopkins University School of Medicine in Baltimore, say they expect it to start working in a matter of months, developing urinary function, sensation and, eventually, the ability to have sex.

From 2001 to 2013, 1,367 men in military service sustained wounds to the genitals in Iraq or Afghanistan, according to the Department of Defense Trauma Registry. Nearly all were under 35 years old and were hurt by homemade bombs, commonly called improvised explosive devices, or I.E.D.s, sometimes losing all or part of their penises or testicles — what doctors call genitourinary injuries…

Dr. Lee cautioned that patients should be realistic and not “think they can regain it all.” But doctors can give the recipients a range of what to expect.

“Some hope to father children,” Dr. Lee said. “I think that is a realistic goal.”