HOME

TheInfoList



OR:

The uterus (from
Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of ...
''uterus'', plural ''uteri'') or womb () is the
organ Organ may refer to: Biology * Organ (biology), a part of an organism Musical instruments * Organ (music), a family of keyboard musical instruments characterized by sustained tone ** Electronic organ, an electronic keyboard instrument ** Hammond ...
in the
reproductive system The reproductive system of an organism, also known as the genital system, is the biological system made up of all the anatomical organs involved in sexual reproduction. Many non-living substances such as fluids, hormones, and pheromones are als ...
of most female
mammal Mammals () are a group of vertebrate animals constituting the class (biology), class Mammalia (), characterized by the presence of mammary glands which in Female#Mammalian female, females produce milk for feeding (nursing) their young, a ...
s, including humans that accommodates the embryonic and
fetal development Prenatal development () includes the development of the embryo and of the fetus during a viviparous animal's gestation. Prenatal development starts with fertilization, in the germinal stage of embryonic development, and continues in fetal devel ...
of one or more embryos until birth. The uterus is a hormone-responsive
sex organ A sex organ (or reproductive organ) is any part of an animal or plant that is involved in sexual reproduction. The reproductive organs together constitute the reproductive system. In animals, the testis in the male, and the ovary in the female ...
that contains
glands In animals, a gland is a group of cells in an animal's body that synthesizes substances (such as hormones) for release into the bloodstream (endocrine gland) or into cavities inside the body or its outer surface (exocrine gland). Structure De ...
in its lining that secrete
uterine milk Uterine glands or endometrial glands are tubular glands, lined by ciliated columnar epithelium, found in the functional layer of the endometrium that lines the uterus. Their appearance varies during the menstrual cycle. During the proliferative ph ...
for embryonic nourishment. In the human, the lower end of the uterus, is a narrow part known as the
isthmus An isthmus (; ; ) is a narrow piece of land connecting two larger areas across an expanse of water by which they are otherwise separated. A tombolo is an isthmus that consists of a spit or bar, and a strait is the sea counterpart of an isthmu ...
that connects to the cervix, leading to the vagina. The upper end, the body of the uterus, is connected to the
fallopian tubes The fallopian tubes, also known as uterine tubes, oviducts or salpinges (singular salpinx), are paired tubes in the human female that stretch from the uterus to the ovaries. The fallopian tubes are part of the female reproductive system. In ot ...
, at the
uterine horns The uterine horns (cornua of uterus) are the points in the upper uterus where the fallopian tubes exit to meet the ovaries. They are one of the points of attachment for the round ligament of uterus (the other being the mons pubis). They also provi ...
, and the rounded part above the openings to the fallopian tubes is the fundus. The connection of the
uterine cavity The uterine cavity is the inside of the uterus. It is triangular in shape, the base (broadest part) being formed by the internal surface of the body of the uterus between the openings of the fallopian tubes, the apex by the internal orifice of the ...
with a fallopian tube is called the
uterotubal junction The uterotubal junction is the connection between the endometrial cavity of the uterus and the fallopian tube (uterine tube) at the proximal tubal opening, the beginning of the intramural part of the fallopian tube. Histologically, the endometrial ...
. The fertilized egg is carried to the uterus along the fallopian tube. It will have divided on its journey to form a blastocyst that will implant itself into the lining of the uterus – the endometrium, where it will receive nutrients and develop into the embryo proper and later fetus for the duration of the pregnancy. In the
human embryo Human embryonic development, or human embryogenesis, is the development and formation of the human embryo. It is characterised by the processes of cell division and cellular differentiation of the embryo that occurs during the early stages of de ...
, the uterus develops from the
paramesonephric duct Paramesonephric ducts (or Müllerian ducts) are paired ducts of the embryo that run down the lateral sides of the genital ridge and terminate at the sinus tubercle in the primitive urogenital sinus. In the female, they will develop to form the fa ...
s which fuse into the single organ known as a simplex uterus. The uterus has different forms in many other animals and in some it exists as two separate uteri known as a duplex uterus. In medicine, and related professions the term ''uterus'' is consistently used, while the Germanic-derived term ''
womb The uterus (from Latin ''uterus'', plural ''uteri'') or womb () is the organ in the reproductive system of most female mammals, including humans that accommodates the embryonic and fetal development of one or more embryos until birth. The u ...
'' is commonly used in everyday contexts. Events occurring within the uterus are described with the term in utero.


Structure

In humans the uterus is located within the pelvic region immediately behind and almost overlying the
bladder The urinary bladder, or simply bladder, is a hollow organ in humans and other vertebrates that stores urine from the kidneys before disposal by urination. In humans the bladder is a distensible organ that sits on the pelvic floor. Urine enters ...
, and in front of the
sigmoid colon The sigmoid colon (or pelvic colon) is the part of the large intestine that is closest to the rectum and anus. It forms a loop that averages about in length. The loop is typically shaped like a Greek letter sigma (ς) or Latin letter S (thus ''s ...
. The human uterus is pear-shaped and about long, broad (side to side), and thick.Manual of Obstetrics. (3rd ed.). Elsevier 2011. pp. 1–16. . A typical adult uterus weighs about 60 grams. The uterus can be divided anatomically into four regions: the fundus – the uppermost rounded portion of the uterus above the openings of the
fallopian tube The fallopian tubes, also known as uterine tubes, oviducts or salpinges (singular salpinx), are paired tubes in the human female that stretch from the uterus to the ovaries. The fallopian tubes are part of the female reproductive system. In ot ...
s, the body, the cervix, and the
cervical canal The cervical canal is the spindle-shaped, flattened canal of the cervix, the neck of the uterus. Anatomy The cervical canal communicates with the uterine cavity via the internal orifice of the uterus (or internal os) and with the vagina via th ...
. The cervix protrudes into the vagina. The uterus is held in position within the pelvis by
ligaments A ligament is the fibrous connective tissue that connects bones to other bones. It is also known as ''articular ligament'', ''articular larua'', ''fibrous ligament'', or ''true ligament''. Other ligaments in the body include the: * Peritoneal l ...
, which are part of the endopelvic fascia. These ligaments include the pubocervical ligaments, the cardinal ligaments, and the uterosacral ligaments. It is covered by a sheet-like fold of peritoneum, the
broad ligament The broad ligament of the uterus is the wide fold of peritoneum that connects the sides of the uterus to the walls and floor of the pelvis. Structure Subdivisions Contents The contents of the broad ligament include the following: * Reproduc ...
.


Layers

The uterus has three layers, which together form the uterine wall. From innermost to outermost, these layers are the endometrium,
myometrium The myometrium is the middle layer of the uterine wall, consisting mainly of uterine smooth muscle cells (also called uterine myocytes) but also of supporting stromal and vascular tissue. Its main function is to induce uterine contractions. Stru ...
, and
perimetrium The perimetrium (or serous coat of uterus) is the outer serosal layer of the uterus, derived from the peritoneum overlying the uterine fundus, and can be considered a visceral peritoneum. It consists of a superficial layer of mesothelium, and ...
. The endometrium is the inner
epithelial layer Epithelium or epithelial tissue is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. It is a thin, continuous, protective layer of compactly packed cells with a little intercellul ...
, along with its
mucous membrane A mucous membrane or mucosa is a membrane that lines various cavities in the body of an organism and covers the surface of internal organs. It consists of one or more layers of epithelial cells overlying a layer of loose connective tissue. It is ...
, of the
mammal Mammals () are a group of vertebrate animals constituting the class (biology), class Mammalia (), characterized by the presence of mammary glands which in Female#Mammalian female, females produce milk for feeding (nursing) their young, a ...
ian uterus. It has a basal layer and a functional layer; the functional layer thickens and then is shed during the menstrual cycle or estrous cycle. During pregnancy, the
uterine gland Uterine glands or endometrial glands are tubular glands, lined by ciliated columnar epithelium, found in the functional layer of the endometrium that lines the uterus. Their appearance varies during the menstrual cycle. During the proliferative ph ...
s and blood vessels in the endometrium further increase in size and number and form the
decidua The decidua is the modified mucosal lining of the uterus (that is, modified endometrium) that forms every month, in preparation for pregnancy. It is shed off each month when there is no fertilised egg to support. The decidua is under the influe ...
. Vascular spaces fuse and become interconnected, forming the placenta, which supplies
oxygen Oxygen is the chemical element with the chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen Group (periodic table), group in the periodic table, a highly Chemical reaction, reactive nonmetal, and an oxidizing a ...
and nutrition to the embryo and fetus.Blue Histology - Female Reproductive System
. School of Anatomy and Human Biology — The University of Western Australia Accessed 20061228 20:35
The myometrium of the uterus mostly consists of smooth muscle. The innermost layer of myometrium is known as the junctional zone, which becomes thickened in
adenomyosis Adenomyosis is a medical condition characterized by the growth of cells that proliferate on the inside of the uterus (endometrium) atypically located among the cells of the uterine wall ( myometrium), as a result, thickening of the uterus occurs. ...
. The perimetrium is a
serous In physiology, serous fluid or serosal fluid (originating from the Medieval Latin word ''serosus'', from Latin ''serum'') is any of various body fluids resembling serum, that are typically pale yellow or transparent and of a benign nature. The fl ...
layer of visceral
peritoneum The peritoneum is the serous membrane forming the lining of the abdominal cavity or coelom in amniotes and some invertebrates, such as annelids. It covers most of the intra-abdominal (or coelomic) organs, and is composed of a layer of mesothel ...
. It covers the outer surface of the uterus. Surrounding the uterus is a layer or band of fibrous and fatty connective tissue called the
parametrium The parametrium is the fibrous and fatty connective tissue that surrounds the uterus. This tissue separates the supravaginal portion of the cervix from the bladder. The parametrium lies in front of the cervix and extends laterally between the la ...
that connects the uterus to other tissues of the pelvis.
Commensal Commensalism is a long-term biological interaction (symbiosis) in which members of one species gain benefits while those of the other species neither benefit nor are harmed. This is in contrast with mutualism, in which both organisms benefit fro ...
and mutualistic organisms are present in the uterus and form the uterine microbiome.


Support

The uterus is primarily supported by the
pelvic diaphragm The pelvic floor or pelvic diaphragm is composed of muscle fibers of the levator ani, the coccygeus muscle, and associated connective tissue which span the area underneath the pelvis. The pelvic diaphragm is a muscular partition formed by the lev ...
, perineal body, and urogenital diaphragm. Secondarily, it is supported by ligaments, including the peritoneal ligament and the broad ligament of uterus.The Pelvis
University College Cork Archived fro
the original
on 2008-02-27


Major ligaments

It is held in place by several peritoneal ligaments, of which the following are the most important (there are two of each):


Axis

Normally, the human uterus lies in anteversion and anteflexion. In most women, the long axis of the uterus is bent forward on the long axis of the vagina, against the urinary bladder. This position is referred to as anteversion of the uterus. Furthermore, the long axis of the body of the uterus is bent forward at the level of the internal os with the long axis of the cervix. This position is termed anteflexion of the uterus. The uterus assumes an anteverted position in 50% of women, a retroverted position in 25% of women, and a midposed position in the remaining 25% of women.


Position

The uterus is located in the middle of the pelvic cavity, in the frontal plane (due to the
broad ligament of the uterus The broad ligament of the uterus is the wide fold of peritoneum that connects the sides of the uterus to the walls and floor of the pelvis. Structure Subdivisions Contents The contents of the broad ligament include the following: * Reproduc ...
). The fundus does not extend above the ''
linea terminalis The linea terminalis or innominate line consists of the pubic crest, pectineal line (pecten pubis), the arcuate line, the sacral ala, and the sacral promontory. It is the pelvic brim, which is the edge of the pelvic inlet. The pelvic inlet is ...
'', while the vaginal part of the cervix does not extend below the interspinal line. The uterus is mobile and moves posteriorly under the pressure of a full bladder, or anteriorly under the pressure of a full rectum. If both are full, it moves upwards. Increased intra-abdominal pressure pushes it downwards. The mobility is conferred to it by a musculo-fibrous apparatus that consists of suspensory and sustentacular parts. Under normal circumstances, the suspensory part keeps the uterus in anteflexion and anteversion (in 90% of women) and keeps it "floating" in the pelvis. The meanings of these terms are described below: The sustentacular part supports the pelvic organs and comprises the larger
pelvic diaphragm The pelvic floor or pelvic diaphragm is composed of muscle fibers of the levator ani, the coccygeus muscle, and associated connective tissue which span the area underneath the pelvis. The pelvic diaphragm is a muscular partition formed by the lev ...
in the back and the smaller urogenital diaphragm in the front. The pathological changes of the position of the uterus are: * retroversion/retroflexion, if it is fixed * hyperanteflexion – tipped too forward; most commonly congenital, but may be caused by tumors * anteposition, retroposition, lateroposition – the whole uterus is moved; caused by parametritis or tumors * elevation, descensus, prolapse * rotation (the whole uterus rotates around its longitudinal axis), torsion (only the body of the uterus rotates around) * inversion In cases where the uterus is "tipped", also known as retroverted uterus, the woman may have symptoms of pain during sexual intercourse, pelvic pain during menstruation, minor incontinence, urinary tract infections, fertility difficulties, and difficulty using tampons. A pelvic examination by a doctor can determine if a uterus is tipped.


Blood, lymph, and nerve supply supply

The human uterus is supplied by arterial blood both from the
uterine artery The uterine artery is an artery that supplies blood to the uterus in females. Structure The uterine artery usually arises from the anterior division of the internal iliac artery. It travels to the uterus, crossing the ureter anteriorly, to the ute ...
and the ovarian artery. Another anastomotic branch may also supply the uterus from anastomosis of these two arteries. Afferent nerves supplying the uterus are T11 and T12. Sympathetic supply is from the hypogastric plexus and the ovarian plexus. Parasympathetic supply is from the S2, S3 and S4 nerves.


Development

Bilateral Müllerian ducts form during early human fetal life. In males,
anti-müllerian hormone Anti-Müllerian hormone (AMH), also known as Müllerian-inhibiting hormone (MIH), is a glycoprotein hormone structurally related to inhibin and activin from the transforming growth factor beta superfamily, whose key roles are in growth differen ...
(AMH) secreted from the testes leads to the ducts' regression. In females, these ducts give rise to the
Fallopian tubes The fallopian tubes, also known as uterine tubes, oviducts or salpinges (singular salpinx), are paired tubes in the human female that stretch from the uterus to the ovaries. The fallopian tubes are part of the female reproductive system. In ot ...
and the uterus. In humans, the lower segments of the two ducts fuse to form a single uterus; in cases of uterine malformations this fusion may be disturbed. The different uterine morphologies among the mammals are due to varying degrees of fusion of the Müllerian ducts. Various congenital conditions of the uterus can develop ''in utero''. Though uncommon, some of these are didelphic uterus, bicornate uterus and others. See also List of related male and female reproductive organs.


Function

The reproductive function of the human uterus is to accept a fertilized ovum, which passes through the
uterotubal junction The uterotubal junction is the connection between the endometrial cavity of the uterus and the fallopian tube (uterine tube) at the proximal tubal opening, the beginning of the intramural part of the fallopian tube. Histologically, the endometrial ...
from the
fallopian tube The fallopian tubes, also known as uterine tubes, oviducts or salpinges (singular salpinx), are paired tubes in the human female that stretch from the uterus to the ovaries. The fallopian tubes are part of the female reproductive system. In ot ...
. The fertilized ovum divides mitotically to become a blastocyst, which implants into the endometrium and derives nourishment from blood vessels which develop exclusively for this purpose. The fertilized ovum becomes an embryo, attaches to the wall of the uterus, creates a placenta, and develops into a fetus (gestates) until childbirth occurs. Due to anatomical barriers such as the pelvis, the uterus is pushed partially into the abdomen due to its expansion during pregnancy. Even during pregnancy, the mass of a human uterus amounts to only about a kilogram (2.2 pounds). The uterus also plays a role in sexual response, by directing blood flow to the pelvis, ovaries, and
genitals A sex organ (or reproductive organ) is any part of an animal or plant that is involved in sexual reproduction. The reproductive organs together constitute the reproductive system. In animals, the testis in the male, and the ovary in the female, ...
. There is also some evidence from rat studies that the uterus plays a role in
cognition Cognition refers to "the mental action or process of acquiring knowledge and understanding through thought, experience, and the senses". It encompasses all aspects of intellectual functions and processes such as: perception, attention, though ...
in a similar way to the ovaries. A study on rat models found that when the uterus was removed, the rats performed more poorly on spatial memory tasks. Prof. Bimonte-Nelson, the co-author of the study, explained: "the body's autonomic nervous system, which regulates 'automated' metabolic processes, such as heart rate, breathing, digestion, and sexual arousal, also has links to the uterus and brain." No similar studies have yet been conducted on humans.


Clinical significance

During pregnancy the growth rate of the fetus can be assessed by measuring the fundal height. Some
pathological Pathology is the study of the causes and effects of disease or injury. The word ''pathology'' also refers to the study of disease in general, incorporating a wide range of biology research fields and medical practices. However, when used in t ...
states include: * Accumulation of fluids other than blood or of unknown constitution. One study came to the conclusion that
postmenopausal Menopause, also known as the climacteric, is the time in women's lives when menstrual periods stop permanently, and they are no longer able to bear children. Menopause usually occurs between the age of 47 and 54. Medical professionals often ...
women with endometrial fluid collection on gynecologic ultrasonography should undergo endometrial biopsy if the endometrial lining is thicker than 3 mm or if the endometrial fluid is
echogenic Echogenicity (misspelled sometimes as echogenecity) or echogeneity is the ability to bounce an echo, e.g. return the signal in ultrasound examinations. In other words, echogenicity is higher when the surface bouncing the sound echo reflects increa ...
. In cases of a lining 3 mm or less and clear endometrial fluid, endometrial biopsy was not regarded to be necessary, but endocervical curettage to rule out endocervical cancer was recommended. * Hematometra, which is accumulation of blood within the uterus. * Prolapse of the uterus * Carcinoma of the cervix – malignant neoplasm * Carcinoma of the uterus – malignant neoplasm * Fibroids – benign neoplasms *
Adenomyosis Adenomyosis is a medical condition characterized by the growth of cells that proliferate on the inside of the uterus (endometrium) atypically located among the cells of the uterine wall ( myometrium), as a result, thickening of the uterus occurs. ...
 – ectopic growth of endometrial tissue within the myometrium * Endometritis, infection at the uterine cavity *
Pyometra Pyometra or pyometritis is a uterine infection. Though it is most commonly known as a disease of the unaltered female dog, it is also a notable human disease. It is also seen in female cattle, horses, goats, sheep, swine, cats, rabbits, hamsters, ...
 – infection of the uterus, most commonly seen in dogs * Asherman's syndrome, also known as intrauterine adhesions, occurs when the basal layer of the endometrium is damaged by instrumentation (e.g., D&C) or infection (e.g., endometrial tuberculosis) resulting in endometrial scarring followed by adhesion formation that partially or completely obliterates the uterine cavity * Myometritis – inflammation of the muscular uterine wall.


Malformations

Uterine malformations are mainly congenital malformations, and include '' uterus didelphys'', bicornuate uterus and septate uterus. Congenital absence of the uterus is known as
Müllerian agenesis Müllerian agenesis, also known as Müllerian aplasia, vaginal agenesis, or Mayer-Rokitansky-Küster-Hauser syndrome (MRKH syndrome), is a congenital malformation characterized by a failure of the Müllerian ducts to develop, resulting in a mis ...
.


Surgery

A hysterectomy is the surgical removal of the uterus which may be carried out for a number of reasons including the ridding of tumours both benign and
malignant Malignancy () is the tendency of a medical condition to become progressively worse. Malignancy is most familiar as a characterization of cancer. A ''malignant'' tumor contrasts with a non-cancerous ''benign'' tumor in that a malignancy is not s ...
. A complete hysterectomy involves the removal of the body, fundus, and cervix of the uterus. A partial hysterectomy may just involve the removal of the uterine body while leaving the cervix intact. It is the most commonly performed gynecological surgical procedure.


Other animals

Most animals that lay
eggs Humans and human ancestors have scavenged and eaten animal eggs for millions of years. Humans in Southeast Asia had domesticated chickens and harvested their eggs for food by 1,500 BCE. The most widely consumed eggs are those of fowl, especi ...
, such as birds and reptiles, including most ovoviviparous species, have an
oviduct The oviduct in mammals, is the passageway from an ovary. In human females this is more usually known as the Fallopian tube or uterine tube. The eggs travel along the oviduct. These eggs will either be fertilized by spermatozoa to become a zygote, ...
instead of a uterus. However, recent research into the biology of the
viviparous Among animals, viviparity is development of the embryo inside the body of the parent. This is opposed to oviparity which is a reproductive mode in which females lay developing eggs that complete their development and hatch externally from the m ...
(not merely ovoviviparous)
skink Skinks are lizards belonging to the family Scincidae, a family in the infraorder Scincomorpha. With more than 1,500 described species across 100 different taxonomic genera, the family Scincidae is one of the most diverse families of lizards. S ...
''
Trachylepis ''Trachylepis'' is a skink genus in the subfamily Mabuyinae found mainly in Africa. Its members were formerly included in the " wastebin taxon" '' Mabuya'', and for some time in '' Euprepis''. As defined today, ''Trachylepis'' contains the cla ...
ivensi'' has revealed development of a very close analogue to
eutheria Eutheria (; from Greek , 'good, right' and , 'beast'; ) is the clade consisting of all therian mammals that are more closely related to placentals than to marsupials. Eutherians are distinguished from noneutherians by various phenotypic trai ...
n mammalian placental development. In monotremes, mammals which lay eggs, namely the platypus and the
echidna Echidnas (), sometimes known as spiny anteaters, are quill-covered monotremes (egg-laying mammals) belonging to the family Tachyglossidae . The four extant species of echidnas and the platypus are the only living mammals that lay eggs and the ...
s, either the term ''uterus'' or ''oviduct'' is used to describe the same organ, but the egg does not develop a placenta within the mother and thus does not receive further nourishment after formation and
fertilization Fertilisation or fertilization (see spelling differences), also known as generative fertilisation, syngamy and impregnation, is the fusion of gametes to give rise to a new individual organism or offspring and initiate its development. Proc ...
.
Marsupials Marsupials are any members of the mammalian infraclass Marsupialia. All extant marsupials are endemic to Australasia, Wallacea and the Americas. A distinctive characteristic common to most of these species is that the young are carried in a ...
have two uteri, each of which connect to a lateral vagina and which both use a third, middle "vagina" which functions as the birth canal. Marsupial embryos form a choriovitelline placenta (which can be thought of as something between a monotreme egg and a "true" placenta), in which the egg's yolk sac supplies a large part of the embryo's nutrition but also attaches to the uterine wall and takes nutrients from the mother's bloodstream. However, bandicoots also have a rudimentary chorioallantoic placenta, similar to those of placental mammals. The fetus usually develops fully in placental mammals and only partially in marsupials including
kangaroo Kangaroos are four marsupials from the family Macropodidae (macropods, meaning "large foot"). In common use the term is used to describe the largest species from this family, the red kangaroo, as well as the antilopine kangaroo, eastern g ...
s and
opossum Opossums () are members of the marsupial order Didelphimorphia () endemic to the Americas. The largest order of marsupials in the Western Hemisphere, it comprises 93 species in 18 genera. Opossums originated in South America and entered North ...
s. In marsupials the uterus forms as a duplex organ of two uteri. In monotremes such as the platypus, the uterus is duplex and rather than nurturing the embryo, secretes the shell around the egg. It is essentially identical with the shell gland of birds and reptiles, with which the uterus is homologous. In mammals, the four main forms of the uterus are: duplex, bipartite, bicornuate and simplex.Lewitus, Eric, and Christophe Soligo.
Life-history correlates of placental structure in eutherian evolution
." Evolutionary Biology 38.3 (2011): 287-305.
; Duplex: There are two wholly separate uteri, with one fallopian tube each. Found in marsupials (such as
kangaroo Kangaroos are four marsupials from the family Macropodidae (macropods, meaning "large foot"). In common use the term is used to describe the largest species from this family, the red kangaroo, as well as the antilopine kangaroo, eastern g ...
s,
Tasmanian devil The Tasmanian devil (''Sarcophilus harrisii'') (palawa kani: purinina) is a carnivorous marsupial of the family Dasyuridae. Until recently, it was only found on the island state of Tasmania, but it has been reintroduced to New South Wales i ...
s,
opossum Opossums () are members of the marsupial order Didelphimorphia () endemic to the Americas. The largest order of marsupials in the Western Hemisphere, it comprises 93 species in 18 genera. Opossums originated in South America and entered North ...
s, etc.), rodents (such as
mice A mouse ( : mice) is a small rodent. Characteristically, mice are known to have a pointed snout, small rounded ears, a body-length scaly tail, and a high breeding rate. The best known mouse species is the common house mouse (''Mus musculus ...
, rats, and guinea pigs), and
lagomorpha The lagomorphs are the members of the taxonomic order Lagomorpha, of which there are two living families: the Leporidae (hares and rabbits) and the Ochotonidae (pikas). The name of the order is derived from the Ancient Greek ''lagos'' (λαγ ...
( rabbits and hares). ; Bipartite: The two uteri are separate for most of their length, but share a single cervix. Found in ruminants ( deer, moose, elk etc.),
hyrax Hyraxes (), also called dassies, are small, thickset, herbivorous mammals in the order Hyracoidea. Hyraxes are well-furred, rotund animals with short tails. Typically, they measure between long and weigh between . They are superficially simil ...
es,
cat The cat (''Felis catus'') is a domestic species of small carnivorous mammal. It is the only domesticated species in the family Felidae and is commonly referred to as the domestic cat or house cat to distinguish it from the wild members of ...
s, and horses. ; Bicornuate: The upper parts of the uterus remain separate, but the lower parts are fused into a single structure. Found in dogs,
pig The pig (''Sus domesticus''), often called swine, hog, or domestic pig when distinguishing from other members of the genus '' Sus'', is an omnivorous, domesticated, even-toed, hoofed mammal. It is variously considered a subspecies of ''Sus ...
s,
elephant Elephants are the largest existing land animals. Three living species are currently recognised: the African bush elephant, the African forest elephant, and the Asian elephant. They are the only surviving members of the family Elephantidae ...
s,
whale Whales are a widely distributed and diverse group of fully aquatic placental marine mammals. As an informal and colloquial grouping, they correspond to large members of the infraorder Cetacea, i.e. all cetaceans apart from dolphins and p ...
s, dolphins, and
tarsier Tarsiers ( ) are haplorhine primates of the family Tarsiidae, which is itself the lone extant family within the infraorder Tarsiiformes. Although the group was once more widespread, all of its species living today are found in Maritime Southe ...
s, and
strepsirrhine Strepsirrhini or Strepsirhini (; ) is a suborder of primates that includes the lemuriform primates, which consist of the lemurs of Madagascar, galagos ("bushbabies") and pottos from Africa, and the lorises from India and southeast Asia. Col ...
primates among others. ; Simplex: The entire uterus is fused into a single organ. Found in higher primates (including
humans Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, culture, a ...
and chimpanzees). Occasionally, some individual females (including humans) may have a bicornuate uterus, a uterine malformation where the two parts of the uterus fail to fuse completely during fetal development. Two uteri usually form initially in a female and usually male fetus, and in placental mammals they may partially or completely fuse into a single uterus depending on the species. In many species with two uteri, only one is functional. Humans and other higher primates such as chimpanzees, usually have a single completely fused uterus, although in some individuals the uteri may not have completely fused.


Additional images

File:Scheme female reproductive system-en.svg, Schematic frontal view of female anatomy File:Gray34.png, Sectional plan of the gravid uterus in the third and fourth month File:Gray38.png, Fetus in utero, between fifth and sixth months. File:Slide4DDD.JPG, Uterus


See also

*
Menopause Menopause, also known as the climacteric, is the time in women's lives when menstrual periods stop permanently, and they are no longer able to bear children. Menopause usually occurs between the age of 47 and 54. Medical professionals often ...
* Artificial uterus * Social uterus * Unicornuate uterus * Uterus-like mass


References


External links

*  – "The Female Pelvis: Organs in the Female and male Pelvis in situ"
Encyclopedia.com

Uterus Anatomy

Uterus Pregnancy
{{Authority control Organs (anatomy) Pelvis Mammal female reproductive system Human female reproductive system Women's health