MALE SUBFERTILITY INDUCED BY ACUTE SCROTAL HEATING AFFECTS EMBRYO QUALITY IN NORMAL FEMALE MICE

The aim of this experiment was to design a suitable mouse model for ma le subfertility in which to study the effect of decreased sperm qualit y on embryo quality in vivo and in vitro, To achieve male subfertility , testes of adult male mice were immersed in water at either 42 degree s C (heated) or 33 degrees C (controls) during 20 min,Twenty-eight day s after treatment, all heat stressed males showed a significant decrea se in relative testis weight [384.7 mg in controls (286.7-460.6) versu s 323 mg in stress heated groups (117.9-405.6); P < 0.001], sperm conc entration [3.75x10(6)/ml (2.75-7.25) versus 1.00x10(6)/ml (0-4.00); P < 0.001] and progressive sperm motility [57.5% (48.0-79.0) versus 42.5 % (14.0-66.0); P < 0.001], Moreover, after mating to heat exposed male s, not only the number of pregnant females (20/22 versus 18/30) but al so the weight of their embryos [275.4 mg (78.7-339.4) versus 261.8 mg (68.1-339.0); P < 0.001] was significantly lower at 14.5 days post coi tum when compared to controls, Neither the number of resorption sites nor the number of viable embryos per pregnant female was significantly different between groups, Also, the in-vitro fertilization rate of oo cytes, fertilized by spermatozoa collected from heat stressed males, w as significantly lower (44.9%; P < 0.0001) when compared to controls ( 65.1%; P < 0.0001), In conclusion, the results of this study suggest t hat male subfertility induced by acute scrotal heating may result in i mpaired sperm quality, reduced embryo weight in vivo and decreased fer tilization rate in vitro.