Fallopian tube - Fallopian tube

Japanese: 卵管 - らんかん

A tube that receives eggs released from an animal's ovaries and carries them to the genital opening; also called the oviduct. The oviducts of amphibians and other vertebrates are embryologically derived from the Mullerian duct, while the oviducts of fish and invertebrates are generally an extension of the ovarian capsule. In mammals, which are viviparous, most of the oviduct differentiates into the uterus and vagina to maintain the fetus, so the remaining part excluding these two parts is called the oviduct (or trumpeter tube) in the narrow sense, and this is where fertilization occurs. In oviparous animals, nutrients, eggshells, etc. are secreted from the oviduct wall to provide them to the eggs. The ovaries of insects and other animals consist of a collection of several long, thin tubes, and these tubes are called the oviduct (or ovariole), with the part from the end of the ovary being called the oviduct.

[Takao Mori]

Fallopian tube in humans

In humans, the fallopian tubes are paired, one on each side, and begin at the lateral corners of the fundus of the uterus and run toward the pelvic sidewall (7–15 cm long). The fallopian tubes are surrounded by the peritoneum along their entire length, forming the mesoalpinx, which, like the mesoalpinx of the other visceral organs, continues into the uterine broad ligament. The mesoalpinx is the upper border of the uterine broad ligament. The fallopian tubes are supported by the mesoalpinx. The inner end of the fallopian tube is the cervical os, which opens into the uterine cavity, and the outer end is the peritoneal os, which opens into the peritoneal cavity. The fallopian tube is structurally divided into four parts. The innermost part is the uterine part, which is located inside the uterine wall, followed by the isthmus, which is 3–4 cm long and is the narrowest part of the fallopian tube. From here, the fallopian tube gradually expands to become the ampulla. This part is 7–8 cm long, making up almost two-thirds of the total length of the fallopian tube, and arches around the ovary from above and in front. The ampulla of the fallopian tube then transitions into a funnel-shaped infundibulum, which becomes petal-like and opens into the peritoneal cavity. This petal-like part is called the fimbria of the fallopian tube. One of the petals of the fimbria of the fallopian tube extends long and attaches to the upper surface of the ovary, specifically called the fimbria of the ovary. The upper inner surface of the ovary is covered by the fimbria like a tuft, so the eggs released from the inner surface of the ovary are successfully sucked into the fallopian tube.

Fertilization occurs in the ampulla of the fallopian tube. The fertilized egg develops as it travels through the fallopian tube to the uterus and then implants in the uterine wall. The inner surface of the fallopian tube is covered with mucous membrane, and the mucosal epithelium of the infundibulum and fimbria in particular has many cilia, which help transport the egg. The mucous membrane of the fallopian tube also has many longitudinal folds (called tubal folds), which are particularly developed in the ampulla of the fallopian tube. The outside of the mucosa is made up of a hard, thick inner circular layer and an outer longitudinal layer of smooth muscle, and the peristaltic movement of the fallopian tube caused by the contraction of these muscles helps transport the egg. When an egg does not enter the fallopian tube and is fertilized in the peritoneal cavity, this is called a peritoneal pregnancy. In rare cases, a fertilized egg may develop in the fallopian tube for some reason. This is called a tubal pregnancy, and can pose the risk of tubal miscarriage or tubal rupture. In addition, if the fallopian tubes are closed due to a bacterial infection such as salpingitis, it can cause infertility.

In addition, the fallopian tubes were formerly called trumpet tubes due to their shape, and are also called Fallopian tubes or Fallovian tubes after their discoverer, the Italian anatomist G. Fallopio (1523-1562).

[Kazuyo Shimai]

[Reference items] | Ectopic pregnancy | Genital organs

Names of parts of the uterus
©Shogakukan ">

Names of parts of the uterus

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

Japanese:

動物の卵巣から排卵された卵を受け取り生殖孔まで運ぶ管のことで、輸卵管ともいう。両生類以上の脊椎(せきつい)動物の卵管は発生学的にはミュラー管に由来し、魚類や無脊椎動物の卵管は一般に卵巣被膜が伸長したものである。胎生である哺乳(ほにゅう)類の卵管は胎児維持のためにその大部分が子宮と腟(ちつ)に分化するので、この両部分を除いた残りの部分を狭義に卵管（またはラッパ管）とよび、そこが受精の場である。卵生の動物では卵管壁より栄養、卵殻などを分泌して卵に与える。昆虫などの卵巣は何本かの細長い管の集合からなり、この管を卵管（または卵巣管）とよび、卵巣の末端部から先を輸卵管とよんでいる。

［守　隆夫］

ヒトにおける卵管

ヒトの卵管は左右1対になっており、子宮底の左右外側角から始まり、骨盤側壁に向かって延びている（長さは7～15センチメートル）。卵管はその全長にわたって腹膜に包まれ、他の内臓の間膜と同じように卵管間膜を形成し、そのまま子宮広間膜に続く。つまり、卵管間膜は子宮広間膜の上縁にあたる。卵管はこの卵管間膜によって支持されている。卵管の内側端は子宮内腔(くう)に開く卵管子宮口であり、外側端は腹膜腔に開く卵管腹腔口である。卵管は構造上、全長を4区分する。最内側は子宮壁内にある子宮部で、これに続いて卵管峡部がある。これは長さ3～4センチメートルで、卵管中でもっとも狭い部分である。卵管は、ここからしだいに膨大となり、卵管膨大部となる。この部分の長さは7～8センチメートルで、卵管全長のほぼ3分の2を占め、卵巣を前上方からアーチ型に囲んでいる。続いて卵管膨大部は漏斗(ろうと)状の卵管漏斗に移行し、花弁状になって腹膜腔に開く。この花弁状の部分を卵管采(さい)という。卵管采の花弁の1本は長く延びて卵巣の上端表面に付着するが、これはとくに卵巣采とよばれる。卵巣の上端内側面はこの卵管采によって房(ふさ)をかぶせたように覆われるため、卵巣の内側面から排出された卵は、うまく卵管内に吸引されることとなる。

　受精は卵管の膨大部で行われる。受精卵は卵管内を子宮に向かう間に発育し、子宮壁に着床する。卵管の内面は粘膜で覆われるが、とくに卵管漏斗や卵管采の粘膜上皮には多数の線毛があり、この線毛運動は卵の輸送に役だっている。また、卵管の粘膜には縦走するヒダが多く（これを卵管ヒダという）、卵管膨大部でとくに発達している。粘膜の外側には固くて厚い内輪層と外縦層の平滑筋が発達し、この筋の収縮による卵管の蠕動(ぜんどう)運動が卵の輸送を助けている。卵が卵管に入らず、腹膜腔で受精してしまう場合を腹腔妊娠(にんしん)という。また、まれには、なんらかの原因で受精卵が卵管内で発育してしまうことがある。これを卵管妊娠といい、卵管流産とか卵管破裂などの危険を生じる場合がある。このほか、細菌感染によっておこる卵管炎などで卵管が閉鎖されると、不妊症の原因となることもある。

　なお、卵管はその形状から古くはラッパ管とよばれたほか、発見者であるイタリアの解剖学者ファロピーオG. Fallopio（1523―1562）にちなみ、ファロピーオ管あるいはファロビウス管ともよぶ。

［嶋井和世］

[参照項目] | 子宮外妊娠 | 性器

子宮の各部名称

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