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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. ==Macrostructure== The myometrium is located between the endometrium (the inner layer of the uterine wall), and the serosa or perimetrium (the outer uterine layer). Myometrium has 3 layers: Outer made of longitudinal smooth muscles, middle from crisscrossing (figure of eight) muscle fibres and inner circular fibres.〔Miller-Keane Encyclopedia & Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition.〕 Middle crisscross fibres act as living ligature during involution of uterus and prevent blood loss. The inner one-third of the myometrium (termed the ''junctional'' or ''sub-endometrial'' layer) appears to be derived from the Müllerian duct, while the outer, more predominant layer myometrium appears to originate from non-Mullerian tissue, and is the major contractile tissue during parturition and abortion. Also, the junctional layer appears to function like a circular muscle layer, capable of peristaltic and anti-peristaltic activity, equivalent to the muscular layer of the intestines.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Myometrium」の詳細全文を読む スポンサード リンク
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