#fromGENEtoSCREEN #colorectalcancer #GITwitter
This will be the first of many tweetorials regarding colorectal cancer, focused on prevention.
We will try to understand and interrelate as many concepts as possible.
Feel free to add, discuss, correct, and even troll 🤣
EPISODE 1
Colonic histology:
The colon is composed of the four layers characteristic of the gastrointestinal tract. Mucosa, submucosa, muscularis propria and serosa
The MUCOSA consists of two types of cells: absorptive cells and mucus-secreting goblet cells. These are arranged in closely packed straight tubular glands or crypts (of Lieberkuhn), which extend to the muscularis mucosa. Lamina Propria: abundant between cross-sections of...
...the crypts. And finally the Muscularis Mucosae (MM): which is a layer of smooth muscle (not to be confused with the Muscularis Propria or Externa)
COLOR CODE:
GREEN: Glands/Crypts
RED: Lamina Propria
ORANGE: Muscularis Mucosae
Look at the en-face cut I drew "with love" ☺️ using the same color code
DISGRESSION 1:
The crypt openings or pits have different "shapes" or patterns, and those patterns allow us to, in vivo (during colonoscopy), understand or predict what is happening with those glands (remember Kudo patterns?)
END OF DISGRESSION
Finally, the submucosa (SM) has dense irregular connective tissue with blood vessels, lymphatic vessels, and nerves (Meissner's plexus)
DISGRESSION 2:
Measurement of deep invasion (>1000microns) into the submucosa can be a predictor of lymph node involvement in T1 cancer. When MM can be identified, SM invasion should be measured from the bottom of the MM to the invasive front of the tumor.
END OF DISGRESSION
Coming back to our beloved crypts
The epithelium contains large numbers of cryptal cells. Differentiated cells (enterocytes, enteroendocrine and goblet) occupy the crypt. The remaining part of the crypts is made up of stem cells and the proliferating progenitor compartment
The colonic epithelium is the most rapidly self-renewing tissue in adult mammals (the process takes 2-3 days). Epithelial renewal occurs in the crypts through a coordinated series of events such as proliferation, differentiation and migration toward the large intestinal lumen.
One of the mitotic stem cells remains as a stem cell at the bottom of crypt and another cell is gradually pushed up to the luminal surface as an epithelial cell. The cells that reached the uppermost part execute apoptosis and peel off without replicating or differentiating.
Probably the control of stem cell proliferation and the dysregulation of this proliferation leads to colorectal cancer...
NEXT EPISODE: Pathways of colorectal carcinogenesis. Don't miss it.
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NEXT EPISODE:
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