author(s)
Amer M Hussin and AG Al-Haaik

abstract
The objective of this study was to focus the light on the events of angiogenesis during spring and summer times. For this purpose, testes of ten rams were collected from Baghdad in spring and summer seasons in 2017.Samples were histologically processed and prepared for light microscopy. Hematoxylin and eosin stain was used for staining. The results revealed that the process of angiogenesis was took place during studied seasons, summer and spring. The onset of angiogenesis occurred firstly during spring and then lasted during summer; however it is more prominent in summer time. The diameters of capillaries in spring and summer were similar, while diameters and thickness of arterioles were larger in summer compared to spring. The testicular interstitial tissue in summer time was (24%) represented more than twice that of spring time (11%). The physiological increase in testicular vascularization was more than 2.5 fold in summer time (9.5%) compared to spring time (3.7%). The diameter and thickness wall of arterioles in summer time was higher than in spring. The interstitium and its constituents were more in summer time than in spring time. The study revealed the presense of close relationship between the pre-existing endothelium and pericytes to achieve the events of angiogenesis. These two cell types were mostly involved in the process of angiogenesis. The present study hypothesized that the event of angiogenesis was thrown into four steps.