One of the problems that can develop during a
development of the gut is a condition
known as pyloric stenosis. The pyloric muscle
is a strong muscle which closes the exit to
the stomach. And if this muscle is overdeveloped,
then a variety of consequences can arise.
When the baby feeds, the stomach will distend
and it reaches a certain point where the distention
will turn into a strong contraction and projectile
vomiting can take place. This is spectacular
in a baby, and they can project and they’ll
cover several metres. This is as opposed to
milk dribbling from the mouth as one may find
in the case of tracheoesophageal fistula with
esophageal atresia which we covered in the
lecture in lung development. This condition
is more common in males than in females, and
will generally occur a few weeks after birth.
A mass can be felt in the abdomen, about the size
of an olive, and this condition is relatively
straightforward to deal with surgically. However,
if left untreated, it could in fact prove fatal.
Another set of complications can arise at
the hind end of the gut. If the anal canal
fails to open to the outside, there’ll be
a blind ending to the gut, and the baby will
be unable to pass bowel movements after birth.
This condition may remain as a blind ending,
but another series of possibilities are that
they can form an exit through another part
of the body. The blind endings are illustrated
in diagrams A and B. But if we’re to look
at diagrams C and D, we can see in there that
in the first one, in C, then the gut is exiting
in an abnormal position closer to the perineum.
And in D, it’s exiting through the vagina.
This would mean that the baby will be producing
bowel movements at the vagina instead of in
the normal anal situation. In image E, then the
bowel is connected by a fistula to the urethra,
and therefore, the bowel movements will emerge
from the end of the penis in this male child.
Conversely, the fistula may be present in the bladder.
Again, this may be corrected surgically.
So, in this lecture, we’ve looked at the developments
of the stomach, the midgut
and the midgut loop, the hindgut, and some
abnormalities of these structures.