Human Male human male 79 article 75 Female 73 Support, Non-U.S. Gov't 71 priority journal 56 Adult 53 female 53 Middle Age 49 adult 47 Aged 30 controlled study 30 human cell 30 Adolescent 29 Child 27 major clinical study 24 Animal 22 Child, Preschool 21 aged 20 adolescent 19 Spermatozoa 18 clinical article 18 child 17 Time Factors 16 case report 16 Case Report 12 Comparative Study 12 Rats 12