Wye branch (Y branch) x X-Band X-chromosome X inactivation X-linked X-linked disease X-Ray Background X-Ray Burst X-ray crystallography X-Ray Flare Class X-Rays xanthophyll XBT XCITED
| XCPT xenia xenobiotic xenogeneic xenograft xenotransplantation Xenotransplantion Xeriscape xerophyte XPC XSEC xylem Y-chromosome YAC YDA
|