Tsumori Toshiko, Tsumiyama Wakako
Departments of Nursing, Faculty of Health and Welfare, Prefectural University of Hiroshima, Mihara, Japan.
Physical Therapy, Faculty of Health and Welfare, Prefectural University of Hiroshima, Mihara, Japan.
Anat Rec (Hoboken). 2017 Nov;300(11):2058-2069. doi: 10.1002/ar.23627. Epub 2017 Jul 17.
The external urethral sphincter is a unique striated muscle surrounding the urethra that plays a crucial role in urinary continence, and a comprehensive understanding of its morphology is needed to determine the pathophysiology underlying urinary incontinence and find suitable therapies. Differences between the sexes and among species regarding the fiber types present remain controversial. This study used triple immunofluorescence labeling to visualize one slow (Type 1) and two fast (Types 2A and 2B) myosin isoforms in rat external urethral sphincters from both sexes. Type 2A fibers predominated throughout the sphincter and Type 2B fibers were restricted to the proximal one-third of the external urethral sphincter in the female rats. Type 1 fibers were present adluminally and were concentrated in the proximal and distal segments of the sphincter. While most of the male external urethral sphincter comprised Type 2B fibers, Type 2A fibers intermingled among these fibers in the proximal one-third of the sphincter, and a few Type 1 fibers were present that were restricted to the adluminal region of the proximal segment. The fiber-type compositions and their areal densities changed in both sexes after gonadectomy. The areal density of the Type 1 fibers increased significantly in the ovariectomized females, especially in the distal segment. In the orchidectomized males, the areal densities of the Types 1 and 2A fibers increased significantly, but that of the Type 2B fibers decreased. These results indicate that myosin heavy chain expression in the rat external urethral sphincter is sexually dimorphic and shows regional differences. Anat Rec, 2017. © 2017 Wiley Periodicals, Inc. Anat Rec, 300:2058-2069, 2017. © 2017 Wiley Periodicals, Inc.
尿道外括约肌是围绕尿道的独特横纹肌，在尿失禁中起关键作用，需要全面了解其形态以确定尿失禁的病理生理学并找到合适的治疗方法。关于存在的纤维类型在性别和物种之间的差异仍存在争议。本研究使用三重免疫荧光标记来观察大鼠两性尿道外括约肌中的一种慢肌球蛋白亚型（1型）和两种快肌球蛋白亚型（2A型和2B型）。在雌性大鼠中，2A型纤维在整个括约肌中占主导，而2B型纤维局限于尿道外括约肌近端三分之一处。1型纤维位于管腔内，集中在括约肌的近端和远端节段。虽然雄性尿道外括约肌大部分由2B型纤维组成，但在括约肌近端三分之一处，2A型纤维夹杂在这些纤维中，并且有一些1型纤维仅存在于近端节段的管腔区域。性腺切除术后，两性的纤维类型组成及其面积密度均发生变化。在去卵巢雌性大鼠中，1型纤维的面积密度显著增加，尤其是在远端节段。在去势雄性大鼠中，1型和2A型纤维的面积密度显著增加，但2B型纤维的面积密度降低。这些结果表明，大鼠尿道外括约肌中的肌球蛋白重链表达具有性别差异并呈现区域差异。《解剖学记录》，2017年。©2017威利期刊公司。《解剖学记录》，300:2058 - 2069，2017年。©2017威利期刊公司。
