Experimental Studies on Morphological Changes of the Epididymis and Testis in Neonatally Estrogenized Mice Revisited

Our primary concern in this review is to give possible explanations and pose new questions on the phenomena concerning eff ects of neonatal estrogen exposure on the development and functions of reproductive organs and immune mechanisms particularly in male animals, in the light of new fi ndings and cencepts. At fi rst, our own experimental results on the pathological changes in the epididymis and testis in neonatally estrogenized mice have been presented. The results of our fi rst experiment showed that neonatal single injection of 10 μg of estradiol benzoate induced marked infl ammatory changes in the epididymis and testis, in which the initial pathological change occurred concomitantly with the appearance of sperms in the epididymal duct. The second experiment showed that such epididymo-testicular changes did not occur when the testis was removed or neonatal estrogen was followed by testosterone. From these results, a possibility was suggested that a hormone-related autoimmune mechanism might participate in such changes. Relating to these, various reports concerning eff ects of neonatal estrogen treatment, either alone or with concommitent treatment with androgen, on the development and functions of reproductive organs and immune mechanisms in the adolescent or adult have been reviewed. In addition, advances in the related areas, such as estrogen-related mechanisms in the development and functions of reproductive organs and immune mechanisms including autoimmune disease mechanisms, gender diff erences and the role of CD25 CD4 T lymphocytes have also been reviewed briefl y. Hirosaki Med.J. 59, Supplement:S278―S287,2007