The Research Of The External Urethral Sphincter In The Male

Purpose: The structure of the external sphincter is still a subject of controversial discussion, especial in morphology of the striated muscle of the external sphincter. Experiments in various animals, including rhesus monkeys, are often performed to improve the understanding that of human's. But the results are limited as animal models for human, which do not fit for mankind. Some scholars anatomize the lower urinary tract of human's corpses directly, searching for the anatomy and histomorphology of the bulbourethra. But the structure of the external sphincter is still controversial Therefore, a comparatively detailed study of the lower urinary tract of the male adults was performed to elucidate anatomical of humans.Materials and Methods: We anatomized the lower urinary tract of 5 male bodies. We obtained 4 integrated cases of membranous urethra. We performed histological slices, HE dyeing and immunohistochemical staining to differentiate striated and smooth muscle. We examined the striate muscle carefully with microscope. Then we took the microphotographs and restructured whole transects of membranous urethra with some special image software.Results: We identified the musculature of the transect of urethra. In which we find only smooth muscle around prostate urethra. But there is some striated muscle round prostate envelope. At the apex of prostate, some circular striated muscle can be sighted around urethra, which thickened at posterior-urethra and connected with that of prostate. We also see a small quantity of striated muscle around membranous urethra but more horseshoe-shaped sphincter. At posterior-urethra, some striated longitudinal muscle can be easily detected clinging to horseshoe-shaped sphincter at this level.Conclusions: Due to morphology of the external urethral sphincter of present research, we know that the sphincter in male adults assumes ahorseshoe or omega-shaped or ring-shaped configuration. But with the difficulties of obtaining specimen, warps at slice up and aberrance of singles, we have so little chance to gain a large quantity of realistic data. So we may have some different opinions of the structure of the external sphincter. According to the distributing of striated muscle at transect of urethra, we considered that there do some circular muscle among the prostate urethra and bulbo-urethra. We also see some striated muscle vertically located along posterior-urethra at membranous urethra. And we believe mostly sphincter is horseshoe-shaped and which work with circular portion have primary function.