The cloacal membrane is the membrane that covers the
embryonic cloaca during the
development of the urinary and reproductive organs
The development of the urinary system begins during prenatal development, and relates to the development of the urogenital system – both the organs of the urinary system and the sex organs of the reproductive system. The development continues a ...
.
It is formed by
ectoderm
The ectoderm is one of the three primary germ layers formed in early embryonic development. It is the outermost layer, and is superficial to the mesoderm (the middle layer) and endoderm (the innermost layer). It emerges and originates from t ...
and
endoderm
Endoderm is the innermost of the three primary germ layers in the very early embryo. The other two layers are the ectoderm (outside layer) and mesoderm (middle layer). Cells migrating inward along the archenteron form the inner layer of the gast ...
coming into contact with each other.
As the human embryo grows and
caudal folding continues, the
urorectal septum divides the cloaca into a ventral
urogenital sinus
The urogenital sinus is a part of the human body only present in the development of the urinary and reproductive organs. It is the ventral part of the cloaca, formed after the cloaca separates from the anal canal during the fourth to seventh w ...
and dorsal
anorectal canal. Before the urorectal septum has an opportunity to fuse with the cloacal membrane, the membrane ruptures, exposing the urogenital sinus and dorsal anorectal canal to the exterior. Later on, an ectodermal plug, the
anal membrane, forms to create the lower third of the rectum. It ruptures in the seventh week of gestation.
References
External links
*
*
Diagram at unsw.edu.au
Embryology of urogenital system
Embryology of digestive system
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