Increased Apoptotic Lymphocyte Population in the Spleen of Young Chickens Fed on Diets High in Molybdenum

The experiment was conducted with the objective of examining the effects of high molybdenum (Mo) on the apoptosis of splenic lymphocytes in broilers by the methods of experimental pathology and flow cytometry (FCM). Three hundred 1-day-old avian broilers were divided into four groups of 75 each and were fed on control diet (Mo 13 mg/kg) and high Mo diets (Mo 500 mg/kg, high Mo group I; Mo 1,000 mg/kg, high Mo group II; and Mo 1,500 mg/kg, high Mo group III) for 42 days. The results showed that the relative weight of spleen was decreased, and lymphocytes were histopathologically decreased in high Mo groups II and III. Ultrastructurally, the apoptotic cells showed typical condensed nuclei with dark-round, petal-like, and horseshoe-like shapes. The mitochondria were swelled, and the endoplasmic reticulum and the Golgi apparatus were dilated in high Mo groups II and III. The statistical analyses by FCM indicated that the percentage of cellular apoptosis was higher in high Mo groups II and III than in control group. Also, the TUNEL staining was consistent with the results of FCM. It was concluded that dietary molybdenum in 1,000 and 1,500 mg/kg caused splenic lesions and lymphocyte apoptosis, which could inhibit the development of spleen and could impair immune function in broilers.