They occur in many mammals, including canids,[1] mice,[2] ferrets,[3] rhinoceroses,[4] and even-toed ungulates[5] and produce pheromones.
Male canids scent-mark their territories with urine and preputial gland secretions.
[9][10] They are modified sebaceous glands located around the corona and inner surface of the prepuce of the human penis.
[13] While humans may not have true anatomical equivalents, the term may sometimes be used for tiny whitish yellow bumps occasionally found on the glans corona.
According to detractors, they are not glands, but mere thickenings of the skin and are not involved in the formation of smegma.