Proportions of fiber types in the external urethral sphincter of young nulliparous and old multiparous rabbits

Tokunaka, Sohei; Fujii, Hiromitsu; Hashimoto, Hiroshi; Yachiku, Sunao

doi:10.1007/bf01788830

Cited by 12 publications

(13 citation statements)

References 22 publications

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“…Previously, the fibers from the external sphincter in adults have been identified as 100% slow twitch type by the methods of histochemistry [9] and electrophoresis for myosin isoform [19]. Here we confirm this finding by immunochemistry using a slow twitch-specific antibody.…”

Section: Discussionsupporting

confidence: 77%

Morphometry of the aging female rat urethra

et al. 1996

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Muscles in the limbs change with age, but the aging process of urethral muscles is unknown. Therefore, we compared smooth and striated muscle content in the female rat urethra in young (12 month) and old (32 month) animals, using immunochemical techniques. All the striated skeletal fibers at both ages contain slow myosin. Urethral diameter does not change with age (young, 1.44 +/- 0.08 mm; old, 1.46 +/- 0.10 mm, n = 5), nor does the external sphincter width (young, 0.088 +/- 0.016 mm; old, 0.080 +/- 0.017 mm, n = 5). Neither smooth nor skeletal muscle volume in the urethra is changed with age (skeletal: young, 20.72 +/- 2.94%; old, 19.95 +/- 2.35%. Smooth: young, 22.26 +/- 2.98%; old, 26.75 +/- 2.35%, n = 5). The external striated sphincter is separate and distinct from the pubococcygeal region of the levator ani muscle, but is closely apposed to another layer of longitudinally oriented fibers into the vaginal musculature. The morphometric analysis shows no difference in urethral architecture in aging female rats.

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Section: Discussionsupporting

confidence: 77%

Morphometry of the aging female rat urethra

et al. 1996

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“…However the proportion of fast and slow MHC fibers in urethral striated muscle may varies between species. Studies showed that the striated urethral sphincter of rabbit (Tokunaka et al, 1993) and dog (Augsburger and Cruz-Orive, 1998) present a similar feature we observed in rat urethra, contains a high proportional of fast fibers. On contrary, human sphincter contains a mixture of slow and fast fibers with slow fibers being the dominant type (Tokunaka et al, 1990).…”

Section: Discussionsupporting

confidence: 71%

The Distribution of Muscles Fibers and Their Types in the Female Rat Urethra: Cytoarchitecture and Three‐Dimensional Reconstruction

Lim

Wang

Tseng

et al. 2013

The Anatomical Record

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An attempt to explore urethral cytoarchitecture including the distribution of smooth muscles and fast and slow striated muscles of adult female Sprague Dawley rat-a popular model in studying lower urinary tract function. Histological and immunohistochemical stainings were carried out to investigate the distribution of urethral muscle fibers and motor end plates. The urethral sphincter was furthermore three-dimensionally reconstructed from serial histological sections. The mucosa at the distal urethra was significantly thicker than that of other segments. A prominent inner longitudinal and outer circular layer of smooth muscles covered the proximal end of urethra. Thick circular smooth muscles of the bladder neck region (urethral portion) decreased significantly distalward and longitudinal smooth muscles became 2-to 3-fold thicker in the rest of the urethra. An additional layer of striated muscles appeared externally after neck region (urethra) and in association with motor end plates ran throughout the remaining urethra as the striated sphincter layer. Most striated muscles were fast fibers while relatively fewer slow fibers often concentrated at the periphery. A pair of extraneous striated muscles, resembling the human urethrovaginal sphincter muscles, connected both sides of mainly the distal vagina to the dorsal striated muscles in the wall of the middle urethra. The tension provided by this pair of muscles, and in conjunction with the striated sphincter of the urethral wall, was likely to function to suspend the middle urethra and facilitates its closure. CompreAbbreviations used: AChE 5 acetyl cholinesterase; EUS 5 external urethral sphincter; LUT 5 lower urinary tract; MHC 5 myosin heavy chain; PB 5 phosphate buffer; UVS 5 urethrovaginal sphincter.

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“…However in concordance with our finding, in the female rat other authors have described that the striated musculature that surrounds the urethra forms part of the urethral wall [21]. In the female rabbit, the gross anatomy of the external sphincter has not been described and only schematic diagrams exist of the arrangement of the striated musculature surrounding the urethra and vagina [25].…”

Section: Discussionsupporting

confidence: 77%

“…Additionally, the striated muscle fibers in the distal urethra and pelvic vagina could act similarly to the external sphincter of the urethra during micturition, conferring greater contractile capacity to these regions [18]. In the pelvic vagina, they might also help control the transit speed of fetuses during parturition, avoiding tearing of the vagina and associated structures [25]. For its part, differences in the organization of smooth muscle and the presence or absence of striated muscle along the tract might be associated with regulation of the diverse forms of urination in this species [27].…”

Section: Discussionmentioning

confidence: 99%

General tissue characteristics of the lower urethral and vaginal walls in the domestic rabbit

et al. 2008

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In European rabbits, the distal urethra (DU) opens into the anterior pelvic vagina forming a single canal by which females copulate, give birth, and urinate. We investigated whether the histological characteristics of the DU and the pelvic and perineal vagina are different. The DU and vagina of rabbits (Oryctolagus cuniculus) were cut and stained with hematoxylin-eosin and Masson's trichrome (n = 3). Data were compared by using Friedman's ANOVA for repeated measures. The walls of the DU and vagina are composed of mucosa, submucosa, smooth muscle, and an external layer. Differences in tissue characteristics of the mucosa, orientation of the smooth muscle fibers, components of the external layer (connective tissue, blood vessels, and striated musculature), and thickness of the tissue layers were found among regions. The lack of histological homogeneity along the urethra and vagina possibly reflects differences in the functions of each segment.

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Proportions of fiber types in the external urethral sphincter of young nulliparous and old multiparous rabbits

Cited by 12 publications

References 22 publications

Morphometry of the aging female rat urethra

Morphometry of the aging female rat urethra

The Distribution of Muscles Fibers and Their Types in the Female Rat Urethra: Cytoarchitecture and Three‐Dimensional Reconstruction

General tissue characteristics of the lower urethral and vaginal walls in the domestic rabbit

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