title: Immunophysiology and pathology of inflammation in the testis and epididymis.
abstract: The ability of spermatogenic cells to evade the host immune system and the  ability of systemic inflammation to inhibit male reproductive function  represent two of the most intriguing conundrums of male reproduction. Clearly,  an understanding of the underlying immunology of the male reproductive tract  is crucial to resolving these superficially incompatible observations. One  important consideration must be the very different immunological environments  of the testis, where sperm develop, and the epididymis, where sperm mature and  are stored. Compared with the elaborate blood-testis barrier, the tight  junctions of the epididymis are much less effective. Unlike the seminiferous  epithelium, immune cells are commonly observed within the epithelium, and can  even be found within the lumen, of the epididymis. Crucially, there is little  evidence for extended allograft survival (immune privilege) in the epididymis,  as it exists in the testis, and the epididymis is much more susceptible to  loss of immune tolerance. Moreover, the incidence of epididymitis is  considerably greater than that of orchitis in humans, and susceptibility to  sperm antibody formation after damage to the epididymis or vas deferens  increases with increasing distance of the damage from the testis. Although we  still know relatively little about testicular immunity, we know less about the  interactions between the epididymis and the immune system. Given that the  epididymis appears to be more susceptible to inflammation and immune reactions  than the testis, and thereby represents the weaker link in protecting  developing sperm from the immune system, it is probably time this imbalance in  knowledge was addressed.
authors.affiliation: Monash Institute of Medical Research, Monash University, 27-31 Wright St, Clayton, Victoria, Australia. mark.hedger@monash.edu
authors.forename: Mark P
authors.initials: MP
authors.lastname: Hedger
mesh_terms: D000818:Animals; D001424:Bacterial Infections / Q000276:immunology; D001814:Blood-Testis Barrier / Q000276:immunology; D004822:Epididymis / Q000276:immunology*; D004823:Epididymitis / Q000276:immunology* / Q000382:microbiology; D006801:Humans; D007108:Immune Tolerance; D007111:Immunity, Cellular; D007113:Immunity, Innate; D008297:Male; D051379:Mice; D009920:Orchitis / Q000276:immunology* / Q000382:microbiology; D051381:Rats; D013737:Testis / Q000276:immunology*; D014649:Vas Deferens / Q000276:immunology; D014777:Virus Diseases / Q000276:immunology