Inside the Rectum

The inner part of the rectum presents 2 types of mucosalfolds- temporary and long-lasting.

• Temporary folds are mainly longitudinal and seen in the lower part of the rectum. They evaporate when the rectum distends.
• Long-term folds (or Houston’s valves) are semilunar (crescentic) transverse folds situated against the concavities of the lateral curvatures of the rectum. They’re created by the reduplication of the mucous membrane consisting of submucous tissue and the thickening of the circular smooth muscle of the rectal wall.

The Five Layers of the Rectal Wall

The rectal wall consists of five distinct layers, namely

1. the mucosa (lined by columnar epithelium with a lot of mucous-producing goblet cells)
2. deep mucosa (lamina propria and muscularis mucosae)
3. submucosa
4. muscularis propria (2 thick proper muscle layers; inner circular and outer longitudinal layers)
5. serosa (perirectal fat).

The Secret of Goblet Cells

There are plenty of Goblet Cells lining the mucosal layer of the rectal wall
These Goblet cells are a specialized type of epithelial cell that secrete mucins, which are significant components of mucus – a gel-like secretion.

Mucins are highly glycosylated proteins, which means they have many carbohydrate residues attached to their structure. These carbohydrates give mucus its slimy, gel-like consistency.

Goblet cells work to produce and secrete mucus helping to lubricate increasingly dry poop on the way out of the GI tract.

The mucus is important throughout the gastrointestinal tract for lubricating the surfaces of the tissues that materials must slide down (or up and down as you fuck or fist).

Histological staining of goblet cells. Cells are stained with the Periodic acid–Schiff method, which stains the glycoproteins present in mucus a dark purple color

Mucous within the Goblet Cells, ready to lubricate your rectum.