In the normal condition, intestinal stem cells located in crypts can proliferate asymmetrily, and the produced daughter cells migrate up to villus, together with differentiation and maturation, at last shed at the top of the villus.

Applied anatomy of the operation in frontal recess region under the nasal endoscope;

Objective To observe the distribution pattern of frontal recess cells and to determine the frequency of each category cell in healthy adult.

Frontal recess locates at the anterosuperior part of the ethmoidal labyrinth,the anatomical structure of which is most complicated.

Mobility detection of inferior pole of piriform recess under X-ray and its influence factors analysis;

Measuring the position of inferior piriform recess through X-ray film and its clinical implicatiom;

Anatomic basis of piriform recess locating upper orifice of esophagus;