['To quantify the amount of AR messenger RNA (mRNA) and to analyze the presence and functionality of the AR protein in X- and Y-carrier human spermatozoa.', 'A molecular and cellular research study.', 'Academic research clinic and laboratories.', 'Ten normozoospermic volunteers.', 'Sperm were analyzed for expression of AR mRNA and protein. The functionality of AR protein was assessed after incubation with 1 nM of synthetic androgen.', 'Reverse-transcription polymerase chain reaction (PCR), real-time PCR, Western immunoblotting, confocal immunofluorescence, and fluorescence in situ hybridization analysis were performed.', 'A significant amount of AR mRNA (around 30% of that found in the testis) was found in sperm. Androgen receptor protein was found in both X- and Y-carrier spermatozoa and translocates into the nucleus in the presence of synthetic androgen.'] Is androgen receptor expressed in both X- and Y-carrier human spermatozoa?