Abstract

The study aimed to investigate the effect of season on the skin and cutaneous glands in local Awassi breed of sheep (Ovis ovis). The study was done on five healthy adult rams of Awassi breed in winter and summer at five anatomical regions (armpit, back, scrotum, ventral surface of fatty tail and dorsal surface of the fatty tail). The study explained that season had no significant effect on the histological structure of the sheep's skin, while there was a significant variation in the histological measurements of most structures of skin such as skin layers, sweat and sebaceous glands where the thickness of the corneal layer of the skin varied between the winter and summer seasons ,it was thicker in the winter than in the summer for most of the studied areas, the variation was higher and more significantly at scrotum , where the epidermis was thicker in winter than in summer for most of the few wool areas that included in the study, while in the dense wool areas the epidermis was thicker in summer than in winter. The study also showed that the season has a significant effect on the size of the sweat glands. The size of the sweat glands in the summer appeared to be greater than in the winter and for all areas of study, but the area of the scrotum and the skin of the ventral surface of fatty tail showed the opposite. the season had an effect on the depth of the sweat glands in the dermis. With the exception of the scrotum and the ventral surface of the fatty tail, the sweat glands were deeper in the summer than in the winter for the rest of the study areas. The lining of the sweat glands units was affected by the change of season. In the summer, the height of the cells of the sweat units was increased and for all regions of the study to reached 16.43 micrometers in the scrotum area for the summer while decreased in winter to reached 10.70 micrometers. So, we can say that the sweat glands of the study areas faced the warm climate not only by the increase in the size of the glands and their proximity to the surface in the summer but also by increased functional activity. The sebaceous glands in the area of the ventral surface of the fatty tail had a large difference between the winter and summer followed by the rest of the areas, either the armpit areas and the dorsal surface of the fatty tail did not show any significant difference between the two seasons. Finally, we found the season has been shown to play a significant role in influencing the histological measurements of skin and skin glands.