Cloaca

In animal anatomy, a cloaca /kloʊˈeɪkə/ kloh-AY-kə (plural cloacae /kloʊˈeɪsiː/ kloh-AY-see) is the posterior orifice that serves as the only opening for the digestive, reproductive, and urinary tracts (if present) of certain animals, opening at the vent. All amphibians, birds, reptiles, and a few mammals (monotremes, tenrecs, golden moles, and marsupial moles) have this orifice, from which they excrete both urine and feces; this is in contrast to most placental mammals, which have two or three separate orifices for evacuation. Excretory systems with analogous purpose in certain invertebrates are also sometimes referred to as "cloacae".

The cloacal region is also often associated with a secretory organ, the cloacal gland, which has been implicated in the scent-marking behavior of some reptiles, amphibians, and monotremes.

Etymology

The word comes from Latin, and means sewer derived from cluō, which meant "cleanse".

Birds

Birds reproduce using their cloaca; this occurs during a cloacal kiss in most birds. Birds that mate using this method touch their cloacae together, in some species for only a few seconds, sufficient time for sperm to be transferred from the male to the female. The reproductive system must be re-engorged prior to the mating season of each species. Such regeneration usually takes about a month. Birds generally produce one batch of eggs per year, but they will produce another if the first is taken away. For some birds, such as ostriches, cassowaries, kiwi, geese, and some species of swans and ducks, the males do not use the cloaca for reproduction, but have a phallus. In those, the penis helps ensure water does not wash away the male's sperm during copulation.

Cloaca (embryology)

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 endoderm, 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.

Cloaca (film)

Cloaca is a 2003 Dutch film, directed by Willem van de Sande Bakhuyzen. It is a film adaptation of the 2002 theatre play Cloaca written by Maria Goos, who wrote the scenario for the film as well. The leading roles celebrate men in their 40s who were formerly student friends but since then have let their relationship go stale. They are played by: Goos's husband Peter Blok (Tom), Pierre Bokma (Pieter), Gijs Scholten van Aschat (Joep), and Jaap Spijkers (Maarten). Female roles were played by Caro Lenssen (Laura), Elsie de Brauw (Conny), and Marleen Stolz (Russian prostitute). Eric Schneider acted in a supporting role as Brest, Pieter's boss's boss.

Blok, Bokma, Goos, Scholten van Aschat, and Van de Sande Bakhuyzen know each other from the Toneelacademie Maastricht.

The film was conceived as a made-for-TV film (it was co-financed by the AVRO) but later got a cinema release. It won the public prize for Dutch film at a festival in 2003, and was released on DVD in 2005.

Plot

The career of homosexual art historian Pieter, who has been working as an archivist at a municipality, has been going nowhere for 20 years: he is ignored by his colleagues, and for many years now, as a sort of revenge, he has been taking a painting from the depot in the cellar on his birthday. Brest, his boss's boss, takes Vermeulen out for a meal. Pieter expects good news, but instead hears he must return the paintings: in any case the eight paintings by Van Goppel (who died recently) which all of a sudden have become worth a lot of money. This produces a major problem, because Pieter has sold four of the Van Goppels in order to pay for his apartment.