Age-related changes in testicular morphometry and function in Egyptian donkeys

This study aimed to assess the effects of age on testicular morphometry and function in donkeys. Testes and epididymides of 57 donkeys were harvested immediately after slaughtering. The donkeys were grouped: young (1-4 years old, n = 13); adult (5-15 years old, n = 25) and aged (>15 years old, n = 19). Each testis and epididymis were weighed separately. Testicular volume was calculated. Epididymal sperm was harvested by retrograde flushing method, and sperm parameters were evaluated. The testicular parenchyma was immunolabelled for BAX and COX2. Adult and aged donkeys had greater testicular weight and volume than young (p < .05). Epididymal sperm concentration, motility and viability were greater (p < .05) in adults and aged (931.8 ± 39.3 and 858.2 ± 33.2 × 10⁶ /ml) than in young animals (316.3 ± 72.8 × 10⁶ /ml). Aged donkeys had a higher percentage of morphological sperm defects than the other categories (p < .05). Histological examination revealed the presence of age-related degenerative changes in testicular tissue of donkeys. Aged donkeys had higher COX2 protein expression than adult and young donkeys. BAX protein was overly expressed in adults than aged or young animals. In conclusion, advancement of age affects the testicular morphometry and function in donkeys.