Lizards (Squamata)

Male

Located cranial to the kidneys.
Attached to the dorsal wall by a mesochorium.
In some species, the kidney has a posterior sexual segment that becomes swollen during the breeding season and contributes to seminal fluid.
Right testis lies cranial to the left.
- Intimately connected to the vena cava by short blood vessels.
Left testis lies close to the adrenal gland.
- Has its own testicular blood vessels.

Paired hemipenes
Stored in the base of the tail.
- Visualised externally by bulges at the ventral proximal tail.
Only one hemipene is used during copulation.
- Erected by vascular engorgement and muscular action.
- Everted to protrude through the cloaca.
Sperm passes from the ductus deferens into the male urodeum.
Sperm is then carried in a groove down the hemipene to be deposited in the female cloaca.