內窺鏡，內視鏡一種目測檢查身體通道或中空器官，如結腸、膀胱或胃的內部的儀器 An instrument for examining visually the interior of a bodily canal or a hollow organ such as the colon, bladder, or stomach.
尿道大多數哺乳動物自上尿液從膀胱中排出體外的管道，雄性的精子可從中排出 The canal through which urine is discharged from the bladder in most mammals and through which semen is discharged in the male.
