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Gastrointestinal system
Published in David A Lisle, Imaging for Students, 2012
Most rectal carcinomas are annular or polypoid tumours that invade the wall of the rectum. Tumour invasion occurs through the layers of the rectal wall, i.e. mucosal layer, submucosa and muscularis propria. Tumours that have invaded through the full thickness of the rectal wall may then extend into the surrounding mesorectal fat layer. Tumour may then invade adjacent structures such as bladder or seminal vesicles, or may perforate into the peritoneal cavity. Rectal carcinoma may also spread to regional lymph nodes in the pelvis or metastasize to distant sites, such as abdominal lymph nodes or liver.
General Introductory Topics
Published in Vadim Backman, Adam Wax, Hao F. Zhang, A Laboratory Manual in Biophotonics, 2018
Vadim Backman, Adam Wax, Hao F. Zhang
An organ is formed by a combination of the four basic tissue types. The wall of the alimentary (or gastrointestinal) tract provides a good illustrative example. Its luminal surface is lined by epithelium. Underneath the epithelium, there is a basal lamina. In some organs, a layer of loose connective tissue is present that is called lamina propria. Below it, there is muscularis mucosa, which is a layer of smooth muscle cells. These first three layers (epithelium, lamina propria, and muscularis mucosa) form the mucosa. Underneath the mucosa, we find a layer appropriately named the submucosa—this is another layer of loose connective tissue. A distinction between the lamina propria and the submucosa is that the former's role is to support the function of the epithelium (which means microcirculation, e.g., pericryptal plexus of small arterioles and capillaries wrapping around crypts), while the latter contains larger blood vessels. Muscularis propria is typically a much thicker layer of muscle. In the case of the colon, it is this muscle that drives peristalsis. The outermost layer is either the serosa or adventitia. The serosa is a thin membrane composed of a layer of connective tissue lined, from the peritoneal cavity side, by mesothelial cells. The serosa is found primarily (with some exceptions) in the peritoneal organs (e.g., most of the gastrointestinal tract, with the exception of a part of the esophagus and part of the rectum). The adventitia, on the other hand, is a thicker layer and is a mixture of different types of connective tissue, including the loose connective tissue in which some adipose (fat) tissue might be present. The adventitia is found in the retroperitoneal organs (e.g., part of the esophagus and the rectum). Among the digestive organs, the thoracic esophagus, ascending colon, descending colon, and the rectum are bound by the adventitia, while the rest are bound by the serosa.
The aqueous extract of Ocimum gratissimum leaves ameliorates acetic acid-induced colitis via improving antioxidant status and hematological parameters in male Wistar rats
Published in Egyptian Journal of Basic and Applied Sciences, 2018
Kehinde P. Olamilosoye, Rufus O. Akomolafe, Olumide S. Akinsomisoye, Modinat A. Adefisayo, Quadri K. Alabi
The representative photomicrographs of colon sections of control and treated rats are shown in Fig. 6. The histology of the colon sections of the control rats was structurally normal having the normal epithelial architecture and laminal propria, submucosa and muscularis propria. In contrast, treatment with acetic acid alone resulted in severe epithelial erosion, necrotic and distorted cryptic glands accompanied by marked cellular infiltration by mononuclear cells, degenerative changes in the regions of the colon. The morphological characteristics of the colon of rats treated with AEOGL showed significant amelioration of acetic acid-induced colitis and were comparable to those in control group.