The cloacal membrane normally ruptures leaving only the urogenital
sinus (the urethra and vaginal introitus) open. If mesoderm (which
will become the abdominal muscles) has not separated the ectoderm
from the endoderm between the allantois and the genital tubercle,
rupture of the cloacal membrane leaves the urethra and bladder open
as a plate of mucosa on the lower abdomen. In bladder exstrophy, the
rupture occurs after the uro-rectal septum has separated the
urogenital sinus from the hind gut. What happens if the cloacal
membrane ruptures before the uro-rectal septum has divided the
bladder from the hind gut? See answer.
See an axial plane movie of bladder
See next page of Bladder Exstrophy.
Return to Normal Bladder Development.
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©David A. Hatch, M.D., 1996