内窥镜，内视镜一种目测检查身体通道或中空器官，如结肠、膀胱或胃的内部的仪器 An instrument for examining visually the interior of a bodily canal or a hollow organ such as the colon, bladder, or stomach.
尿道大多数哺乳动物自上尿液从膀胱中排出体外的管道，雄性的精子可从中排出 The canal through which urine is discharged from the bladder in most mammals and through which semen is discharged in the male.
