A number of 24 Japanese quails were divided into two groups in order to observe changes in vascularization and weight of the testes during the reproductive and quiescent periods. Group1 was exposed to a long photoperiod of (Light, Dark) 20hL:4hD (20 hour Light:4hour Light) at 18-24 degrees C while the Group 2 received a short photoperiod of 7hL:17hD at 8-12 degrees C. The blood vessels were filled with colored latex for examination. The results revealed that each testis was mostly nourished by a single testicular artery which was arising solely from the descending aorta. The simple nature of the vessels in the quiescent period became very complex as the testes enlarged in the reproductive stage. Weights of the testes between the groups indicated the fact that the left testis was significantly larger during the reproductive and quiescent sexual periods. Consequently, our study showed that long photoperiods and temperatures significantly affect the vascular development of the testes as it is in the reproductive development.