When {HEAD ~ the coil} is removed from {TAIL ~ an endoscope}, the practitioner or the assistant observes the coil as it is withdrawn and notices the appearance of the stripes as an indication that the distal end of the instrument is not far away 
is removed from
When { HEAD ~ the coil } is removed from { TAIL ~ an endoscope } , the practitioner or the assistant observes the coil as it is withdrawn and notices the appearance of the stripes as an indication that the distal end of the instrument is not far away
OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH