Avian Male Reproductive Tract - Anatomy & Physiology

Testes

Bean-shaped, paired
Lie near the cranial pole of the kidney
Medially, they lie close to the aorta and caudal vena cava.
Each testical suspended by a short mesochorium and surrounded medially by the abdominal air sac.
Left tends to be larger than right in immature birds.
Dimentions increase rapidly with sexual activity.
In the non-breeding season, testes shrink to almost nothing and become hard to visualize.
Dormant testes light brown/yellow in colour, turn white when sexually active.
- In some psittacine species, immature or dormant testes may appear black due to melanocytes located in the interstitium.

Semniferous Tubules