Cloaca (embryology)

Cloaca (embryology)
Cloaca (embryology)
Gray1116.png
Tail end of human embryo thirty-two to thirty-three days old. Cloaca is visible at center left. The endodermal cloaca is labeled with green, while the ectodermal cloaca is seen as a colorless crest on the outside.
Gray's subject #241 1109
Days 15
Precursor endoderm[1]
Gives rise to Urogenital sinus
Code TE E5.4.0.0.0.0.14
MeSH Cloaca

The cloaca is a structure in the development of the urinary and reproductive organs.

The hind-gut is at first prolonged backward into the body-stalk as the tube of the allantois; but, with the growth and flexure of the tail-end of the embryo, the body-stalk, with its contained allantoic tube, is carried forward to the ventral aspect of the body, and consequently a bend is formed at the junction of the hind-gut and allantois.

This bend becomes dilated into a pouch, which constitutes the endodermal cloaca; into its dorsal part the hind-gut opens, and from its ventral part the allantois passes forward.

At a later stage the Wolffian duct and Müllerian duct open into its ventral portion.

The cloaca is, for a time, shut off from the anterior by a membrane, the cloacal membrane, formed by the apposition of the ectoderm and entoderm, and reaching, at first, as far forward as the future umbilicus.

Behind the umbilicus, however, the mesoderm subsequently extends to form the lower part of the abdominal wall and pubic symphysis.

By the growth of the surrounding tissues the cloacal membrane comes to lie at the bottom of a depression, which is lined by ectoderm and named the ectodermal cloaca.

Contents

Additional images

See also

References

External links

This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained within it may be outdated.



Wikimedia Foundation. 2010.

Игры ⚽ Поможем написать курсовую

Look at other dictionaries:

  • Cloaca (disambiguation) — Cloaca is an anatomical feature of some animals. Cloaca may also refer to: Cloaca (art), an artwork by Wim Delvoye Cloaca (embryology), a structure in mammalian development Cloaca (film), a 2003 Dutch film directed by Willem van de Sande… …   Wikipedia

  • Embryology — 1 morula, 2 blastula 1 blastula, 2 gastrula with blastopor …   Wikipedia

  • Cloaca — A common passageway for feces, urine and reproduction. At one point in the development of the human embryo, there is a cloaca. It is the far end of a structure called the hindgut. This structure then divides to form a rectum, a bladder, and… …   Medical dictionary

  • human embryology — ▪ biology Introduction       the process encompassing the period from the formation of an embryo, through the development of a fetus, to birth.       The human body, like that of most animals, develops from a single cell produced by the union of… …   Universalium

  • Development of the urinary and reproductive organs — The development of the urinary and reproductive organs as a part of the prenatal development, concerns the urinary system and sex organs. The latter is a part of the stages of sexual differentiation. The urinary and reproductive organs are… …   Wikipedia

  • Development of the reproductive system — The development of the reproductive system is a part of prenatal development, and concerns the sex organs. It is a part of the stages of sexual differentiation. Because its location to a large extent overlaps the urinary system, the development… …   Wikipedia

  • digestive system, human — Introduction  the system used in the human body for the process of digestion. The human digestive system consists primarily of the digestive tract (alimentary canal), or the series of structures and organs through which food and liquids pass… …   Universalium

  • Cloacal membrane — Tail end of human embryo from fifteen to eighteen days old. Latin membrana cloacalis Gray s …   Wikipedia

  • Definitive urogenital sinus — Urogenital sinus of female human embryo of eight and a half to nine weeks old. (Urogenital sinus labeled at bottom.) …   Wikipedia

  • Urorectal septum — Infobox Embryology Name = PAGENAME Latin = GraySubject = 241 GrayPage = 1109 Caption = Cloaca of human embryo from twenty five to twenty seven days old. Caption2 = System = CarnegieStage = Days = 32 Precursor = GivesRiseTo = MeshName = MeshNumber …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”