31.19
子宮管
子宮または卵管は、卵母細胞が卵巣から子宮へ移動する導管として機能します。各卵管の長さは約 10 ～ 13 cm で、解剖学的には漏斗部、膨大部、峡部、間質部 (または壁内節) に分かれています。漏斗部は漏斗状をしており、腹膜腔に向かって伸びる卵管簾と呼ばれる延長部があります。これらの卵管簾は排卵…
子宮管または卵管は、子宮の両側に10〜13cmの長さの通路があります。
各チューブは、インファンディブルム、アンプラ、および峡部に分かれています。
インファンディブルムは、腹腔内に伸びる線毛と呼ばれる指のような突起で飾られた漏斗状の開口部です。
次は膨大部で、子宮管の長さの半分以上を占める最も広い領域です。
峡部は、子宮管と子宮をつなぐ最も狭い部分です。
排卵の周りでは、子宮管の線毛が卵巣を覆い、その表面を掃引します。
管内では、粘膜上皮からの繊毛が腹水に電流を発生させ、卵子の捕捉を助けます。
上皮内の非繊毛分泌細胞とPEG細胞は、卵子に栄養を与える液体を放出します。
粘膜の周りの平滑筋層は蠕動運動で収縮し、卵子を膨大部を通して移動させることで繊毛の働きを補完します。
通常、精子は膨大部の卵母細胞を受精させてから、峡部を通って子宮に移動します。
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Q1: What are the three main sections of the uterine tube?
The uterine tube is divided into three main sections: the infundibulum, a funnel-shaped opening with finger-like fimbriae; the ampulla, the widest region comprising more than half the tube's length; and the isthmus, the narrowest section connecting to the uterus. Each section plays a distinct role in oocyte transport and fertilization.
Q2: How do fimbriae help capture the oocyte during ovulation?
During ovulation, the fimbriae extend over the ovaries and sweep their surface to capture the released oocyte. These finger-like projections cover the ovary and guide the oocyte into the infundibulum, initiating its journey through the uterine tube toward the uterus.
Q3: Why is the ampulla the most common site of fertilization?
The ampulla is the widest section of the uterine tube and provides an optimal environment for sperm and oocyte to meet. Typically, sperm fertilizes the oocyte in the ampulla before it travels through the isthmus to the uterus, making this region ideal for successful fertilization.
Q4: What role do cilia play in moving the oocyte through the uterine tube?
Ciliated epithelial cells in the uterine tube lining generate currents in the peritoneal fluid that transport the oocyte toward the uterus. These cilia work alongside peristaltic contractions of smooth muscle layers to move the oocyte through the ampulla and toward the isthmus.
Q5: What do secretory and peg cells contribute to oocyte transport?
Nonciliated secretory and peg cells in the uterine tube epithelium release a nourishing fluid that sustains the oocyte during its journey. This fluid provides essential nutrients to the oocyte as it travels from the ampulla through the isthmus to the uterus.
Q6: How do smooth muscle contractions assist oocyte movement?
Smooth muscle layers surrounding the mucosa contract peristaltically, complementing the work of cilia by propelling the oocyte through the uterine tube. These coordinated muscular contractions work with ciliary currents to ensure efficient transport of the oocyte toward the uterus for implantation.
Q7: What happens to the oocyte after fertilization in the ampulla?
After sperm fertilizes the oocyte in the ampulla, the resulting zygote travels through the isthmus, the narrowest part of the uterine tube, before reaching the uterus for implantation a few days later. This journey allows the embryo to develop while traveling to its implantation site.