What parts of the gastrointestinal tract develop from the hindgut?

The hindgut gives rise to the left one-third of the transverse colon, descending colon, sigmoid colon, rectum, and the upper part of the anal canal.

How is the anal canal developed embryologically?

The anal canal has a dual origin: the upper half comes from the hindgut (endoderm), and the lower half comes from the proctodeum (ectoderm). The pectinate line marks their junction.

What are the key differences between the upper and lower halves of the anal canal?

Key differences include epithelium (endodermal vs ectodermal), blood supply (superior vs inferior rectal artery), venous drainage (portal vs systemic), and nerve supply (autonomic vs somatic).

What happens to the mesentery of hindgut derivatives during development?

After rotation, the ascending and descending colon fuse with the posterior abdominal wall and become retroperitoneal, while the sigmoid colon and appendix retain their mesenteries.

What is Hirschsprung’s disease and how is it related to hindgut development?

Hirschsprung’s disease is a congenital megacolon caused by absence of parasympathetic ganglia in the rectosigmoid segment, leading to failure of peristalsis and proximal colonic dilatation.

What is imperforate anus and what causes it?

Imperforate anus is a condition where the anal membrane fails to break down or the anal pit develops improperly, resulting in anal stenosis, gaps, or an absent orifice.

What clinical conditions are associated with retained mesentery in hindgut derivatives?

Retained mesentery, as in the sigmoid colon, can lead to volvulus, where intestinal loops twist and cut off blood supply, causing ischemia.

Hindgut Development – Anal Canal & Pectinate Line

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