Penis of Animals
The penis of Animals is the male copulatory organ and is composed of white fibrous tissue and a little erectile tissue.
Penis of Bull
Penis of Bull extends from the ischial arch forward between the thighs to the umbilical region of the abdominal wall. It is supported by the fascia penis and its prescrotal part is situated in a cutaneous pouch -the prepuce. It is cylindrical in form and measures in an adult bull about 90 cm It may be divided into 3 parts -the root, body and glans.
The root is attached to the lateral parts of the ischial arch by two crura, which converge and unite below the arch to form the root of the penis.
The urethra passes over the arch between the crura, curves forward to become incorporated in the substance of the penis. The body begins at junction of the crura and forms the bulk of the organ.
It is flattened from above downward and it presents four surfaces –dorsal, ventral and two lateral surfaces.
At its origin it is attached to the symphysis ischii by two strong bands -the suspensory ligaments of the penis. Just behind the scrotum it forms a S -shaped curve-the sigmoid flexure in which 30 cm of the penis is folded which is released during erection.
The glans penis is the free end of the organ and is 8 cm long. Its extremity is pointed and twisted.
The twisted end shows ventro-laterally a groove and the urethral process projects as a ridge in the groove. At the end of the process is the external urethral orifice. The penis is principally made up of white fibrous tissue.
It is remarkably dense and firm even in the non-erect condition. The organ undergoes very little enlargement during erection but it becomes more rigid.
Penis of Ram and Buck
The free extremity of penis is very distinctive with well-developed urethral process continued beyond the glans penis in Ram and Buck.
Penis of stallion
Penis of stallion is shorter but has a larger diameter, the length being about 50cm in the quiescent state. It undergoes 50% increase during erection. The erectile tissue is very rich in elastic and muscular tissues and hence very soft.
The glans is enlarged and its base forms a prominent margin -the corona glandis. There is a depression in the glans known as fossa glandis. The urethra protrudes into the fossa glandis as the free urethral process. Dorsal to the urethral process, the fossa forms a diverticulum, the urethral sinus, which is the site of accumulation for smegma.
Penis of Boar
Penis of Boar is resemble in general to that of the bull. The sigmoid flexure however is prescrotal. The cranial part is spirally twisted especially in erection.
Penis of Dog
In the cranial part of penis of dog, there is a bone-os penis, which is grooved ventrally for the lodgment of the urethra.
The glans is very long and is extended over the entire length of the os penis. The cranial part of the glans penis is cylindrical with pointed free end. In the caudal part, there is a rounded enlargement, the bulbous glandis. Both are composed of erectile tissue.
Penis of Rabbit
From the root, the body of the penis first proceeds forward and just before reaching testicles, it almost makes a U turn backward. Therefore the glans penis is directed backward in Rabbit. Its free extremity is known as pars libera.
Penis of Cock
Penis is Absent in Cock. The copulatory apparatus is placed at the ventral aspects of the caudal end of cloaca. It comprises of two papillae of vas deferens, two vascular bodies, a phallus and two lymphatic folds.
