Os penis - Baculum (dog)

3D Model

Baculum (os penis) represents intriguing bone structure present in large number of animals. It is derived from connective tissue and has large interspecies morphological diversity. Function of this bone is widely hypothesized whereas most of the scientists believe it gives the mechanical support to the animal penis. Urethral groove present on the ventral side of the bone is thought to protect the urethra from collapsing during copulation. Small and large-sized bones are found unrelated to the size of the animal but the longer os penis is often found in animals whose copulation is prolonged such as canids. Possible function of baculum involves increased stimulation of female during mating. Most of the females have bone structure counterpart to the os penis. It is placed in clitoris and it is known as os clitoris. Some of the species with os penis include canids, mustelids, sea lions, seals, walrus, rodents, bats and many primates (Stockley, 2012).

Stockley P. The baculum. Curr Biol. 2012 18;22(24):R1032-3.