| LES | <anatomy> A muscular sphincter located at the junction of the oesophagus and the stomach. On closure the lower oesophageal sphincter prevents the back wash (reflux) of stomach acid into the oesophagus where it may damage the mucosa. See: gastrooesophageal reflux disease. (16 Mar 1998) |
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| laboratories | Facilities equipped to carry out investigative procedures. (12 Dec 1998) |
| laboratories, dental | Facilities in which the dentist or his auxiliaries perform services related to treatment not done directly in the patient's mouth. (12 Dec 1998) |
| laboratories, hospital | Hospital facilities equipped to carry out investigative procedures. (12 Dec 1998) |