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The ethmoid air cells consist of numerous thin-walled cavities in the ethmoidal labyrinth [4] that represent invaginations of the mucous membrane of the nasal wall into the ethmoid bone. [3] They are situated between the superior parts of the nasal cavities and the orbits, and are separated from these cavities by thin bony lamellae. [4]
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Invasion of tumours through the layers of the gastrointestinal wall is used in staging of tumour spread. This affects treatment and prognosis. The normal thickness of the small intestinal wall is 3–5 mm, [6] and 1–5 mm in the large intestine. [7] Focal, irregular and asymmetrical gastrointestinal wall thickening suggests a malignancy. [7]
The sigmoid colon is the part of the large intestine after the descending colon and before the rectum. The name sigmoid means S-shaped (see sigmoid; cf. sigmoid sinus). The walls of the sigmoid colon are muscular and contract to increase the pressure inside the colon, causing the stool to move into the rectum.
The intestinal epithelium is the single cell layer that forms the luminal surface (lining) of both the small and large intestine (colon) of the gastrointestinal tract.Composed of simple columnar epithelium its main functions are absorption, and secretion.
The nuclei of the cells (located at the outer edges of the cells lining the walls of the crypts) are stained blue-gray with haematoxylin. As seen in panels C and D, crypts are about 75 to about 110 cells long. The average crypt circumference is 23 cells. [8] From the images, an average is shown to be about 1,725 to 2530 cells per colonic crypt.
The strength of the colon wall is known to decrease with age. [1] Previous theories proposed that impacted fecal matter and certain foods would get stuck in diverticula (thereby causing trauma), which caused poor blood flow, death of the affected intestinal wall cells, and intestinal perforation. [1]
The ethmoidal labyrinth or lateral mass of the ethmoid bone consists of a number of thin-walled cellular cavities, the ethmoid air cells, arranged in three groups, anterior, middle, and posterior, and interposed between two vertical plates of bone; the lateral plate forms part of the orbit, the medial plate forms part of the nasal cavity.