Pathology of the hindgut
From an embryonic point of view the hindgut begins already in the transition from the middle to the last third of the transverse colon, where the blood supply by the superior mesenteric artery ceases and that of the inferior mesenteric artery begins. Since a part of the diseases of this section were already discussed in the preceding paragraph, only the abnormalities of the anus will be mentioned here.
Missing perforation of the anus, anal atresia, fistulas
The development of the anus can be disturbed in a large number of ways. The disorder ranges from a simple membrane at the anal exit (persisting cloacal membrane) to atresias of various lengths. Every newborn, therefore, must be examined to see whether the anus is open. Sometimes the anal atresia is combined with a fistula, which connects the intestine with another structure of the original urogenital sinus. Frequently fistulas form that extend as far as the vagina, the urethra, the bladder or into the perianal region on the outside.
Many shape variations of the liver and the discharging bile passages exist but most of them have no functional importance.
Atresias of the bile passages
One serious abnormality is an atresia of the bile passages. This disorder can occur at any place along the bile passage, from the tiny canaliculi to the discharging bile duct.
Newborns with an atresia of the bile passages develop an icterus shortly after birth. When the cause cannot be corrected, a liver transplantation is necessary.
Pancreas abnormalities can affect only its form but also its function. Form variations are relatively frequent without there being any influence on function.
It happens very seldom that the pancreas forms a ring around the whole duodenum. This disorder is frequently associated with the Down syndrome. Just how the disorder comes about is not known.
Cystic fibrosis (CF)
Cystic fibrosis, or also mucoviscidosis, is the second most frequent hereditary disease. The outflow passages of the exocrine portion of the pancreas become stopped up due to the viscous mucus that characterizes this illness. This leads to a buildup of secretion, the formation of fibrous tissue throughout the whole organ and thus to a pancreas insufficiency.