Researchers have wondered why birds, despite having very high core body temperatures, have internal testes and did not evolve external testes.BIOLOGY OF REPRODUCTION 56, 1570–1575 (1997)- Determination of Testis Temperature Rhythms and Effects of Constant Light on Testicular Function in the Domestic Fowl (Gallus domesticus) It was once theorized that birds used their air sacs to cool the testes internally, but later studies revealed that birds' testes are able to function at core body temperature.
Researchers have wondered why birds, despite having very high core body temperatures have internal testes and did not evolve external testes.BIOLOGY OF REPRODUCTION 56, 1570–1575 (1997)- Determination of Testis Temperature Rhythms and Effects of Constant Light on Testicular Function in the Domestic Fowl (Gallus domesticus) It was once theorized that birds used their air sacs to cool the testes internally, but later studies revealed that birds' testes are able to function at core body temperature