RESUMO
Aging is a biological process affecting mammalian tissues and organs at different rates. The present work was done to study the effect of melatonin as anti-aging therapy on the structure of the testis and the pars distalis. A total number of 25 male albino rats were used. The animals were divided into three groups: group [I] served as a control adult group [6 months age], group [II] was the control aged group [20-months age] and group [III] was treated with melatonin. The specimens of the testis and pituitary glands were prepared for light and electron microscopy. Histological and immunohistochemical techniques were used to examine these organs. It was found that age-related changes occur in the histological immunohistochemistry and ultrastructure of the testis and pituitary gland. Also, treatment with melatonin as anti-oxidant and free radical scavenger caused improvement of these changes in the pituitary gland as well as the testis. The age-related changes that occurred in the testis included progressive involution and germ cells depletion in the seminiferous tubules which contained only Sertoli cells. Ultrastructural apoptotic changes of germ cells increased with aging and abnormal morphology of the resulting sperms were found. This might result in decapacitating sperm function increase in interstitial tissue. Leydig cells exhibited ultrastructural changes which might lead to a decrease in their activity and testosterone production. As regard the pituitary gland; different utrastructural changes occurred in the somatotrophs or GH cells. The ultrastructrual and immunohistochemical studies of gonadotrophs or LH/FSH cells showed marked deterioration with progression of age. Treatment with melatonin from the adult state improved the morphological and ultrastructural changes that occurred with aging