strobila

Japanese: strobila

...The fertilized egg develops into a planula, which attaches to the surface, develops tentacles, and grows into a polyp. Many constrictions form on the side of the polyp's body, forming a strobila that resembles stacked plates. As the tentacles degenerate and are absorbed, they become strobila, one by one, which separate from the tip of the strobila at each constriction and become ephyra, which swim out into the water.

From [Cateworm]

...Therefore, proglottids are divided into three groups: immature proglottids, mature proglottids, and gravid proglottids that have eggs in the uterus. The entire body from the scolex to the end is called a strobila. Since they have no digestive tract, nutrients are absorbed from the body surface through numerous tiny projections called cuticle villi, which have a structure similar to that of human intestinal villi.

From [Body segments]

...In particular, in annelids and arthropods, the segments are called ring segments because they form a ring. If we define a segment as "a part of the body with the same structure that has the same organs and is repeated in the front-to-back direction," then the strobila (transverse divisions) that occur during reproduction in tapeworms and certain coelenterates are also made up of many segments of the same type. However, the origin of these segments is of a completely different nature, and the latter segments can be seen as insect bodies that reproduce asexually in the vertical direction, but do not separate from the mother body and remain as parts of the original individual forever, with the front ones losing their tails and the rear ones losing their heads at the connection point. ...

*Some of the terminology that mentions "strobila" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

Japanese:

…受精卵からプラヌラ幼生になって着生し，触手を生じてポリプになって成長する。ポリプの体側に多くのくびれができ，皿を重ねたようなストロビラstrobilaになる。やがて触手が退化吸収されて成熟すると，ストロビラの先端からくびれごとに1枚ずつ離れ，エフィラ幼生ephyraになって水中に泳ぎ出す。…

【ジョウチュウ(条虫)】より

…したがって片節は，未熟片節，成熟片節，および子宮内に虫卵を有する受胎片節の3群に分けられる。頭節から末端までの全体をストロビラstrobila(片節連体)という。消化管がないので栄養は体表から吸収されるが，これはあたかもヒトの腸絨毛（じゆうもう）に類似した構造の角皮絨毛と呼ばれる微小な無数の突起を通して行われる。…

【体節】より

…ことに環形動物や節足動物ではそれが輪状の環をなしているので環節という。ところで体節をこのように〈同種の器官をそなえて前後の方向に反復する同じ構造の体の一部〉と定義すると，サナダムシやある種の腔腸動物の繁殖時におけるストロビラstrobila(横分体)もまた同型の多くの節からできている。しかしその節の起原はまったく違った性質のもので，いわば後者の分節は縦の方向に無性分殖をした虫体が，母体から離れないでいつまでも元の個体の一部分としてとどまり，その連絡位置で前のものは尾を，後のものは頭を失った姿と見ることができよう。…

※「strobila」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典第２版について | 情報

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