The dog as a model system to study epididymal gene expression

Advances in understanding the role of the epididymis in human sperm maturat ion and fertility are dependent upon the availability of appropriate model systems in which to examine regulatory mechanisms and functions in a contro llable fashion. Of a number of mammalian species studied by us and others, we suggest that the dog epididymis offers an excellent compromise in terms of the similarity of the specific genes expressed to those in the human, th eir mode of regulation, and the availability of tissues suitable for cell c ulture studies. We have developed a set of important tools in the form of e pididymis-specific canine cDNA clones and cell culture methods, with which to examine the functioning of the epididymal epithelial cells in vitro, as well as the expression of specific genes in vivo, under normal and patholog ical conditions (e.g. cryptorchidism). Using this model system, we have ela borated the regional patterns of gene expression in vivo for several of the major secretory protein genes of the canine epididymis, and we have examin ed the importance of androgens and temperature on gene expression in vitro.