En 1680-6433 2008-2177 The effects of follicular fluid on human X Y bearing sperm ratio by Fluorescent in Situ Hybridization (FISH) - Background: Some evidences showed that the secretion of uterine tube vagina and follicular fluid (FF) affects X and Y-chromosome populations. Sperm selection with X or Y chromosome can added to oocyte for gender desired. The isolation of X Y sperm have done and all efforts in this field are done to make culture media similar to in vivo condition. The objective of this study was to find if the FF can influence the ratio of X or Y chromosomes therefore we added human FF to culture media to separate X and Y sperms. Materials and Methods: Normal semen sample from 36 healthy men were selected. Then the samples were divided into control and experimental groups: control group sperms have been incubated with conventional culture media (Ham's F-10) and experimental group with conventional culture media + 10% human FF. For sperm isolation swim up technique was used. After 24 hours of incubation slides smear were prepared. Then we used the Fluorescent in Situ Hybridization (FISH) method to evaluate the effect of follicular fluid on the population ratio of X and Y containing sperms. Results: Although the incubation of sperm in FF and Ham's F-10 increased Y sperm (59.44 % in control and 61.42% in experimental groups) in comparison with X sperm (40.56% in control and 38.5 in experimental groups) significantly (p - FISH technique X Y sperm Follicular fluid Conventional media Swim up. 129 133 Soghra Bahmanpour bahmans@sums.ac.ir No Mohammad Reza Namavar - No Tahereh Talaei No Zohreh Mazaheri No Ahmad Monabati No