Department of Anatomy, Catholic Kwandong University College of Medicine, Gangneung, Korea.
Department of Hospital Medicine, College of Medicine, Yonsei University, Seoul, Korea.
Prostate. 2020 May;80(6):471-480. doi: 10.1002/pros.23961. Epub 2020 Feb 12.
The shape and function of the longitudinal muscular column (LMC) of the prostate have not been established in detail. The present study was undertaken to elucidate the roles of the LMC of the posterior wall of the prostatic urethra (PSU) in the emission phase of ejaculation by investigating the form and muscular arrangement of the LMC.
Prostates and urinary bladders were obtained from 14 Korean adult cadavers. Nine specimens were histologically analyzed using hematoxylin and eosin, Masson's trichrome, and Verhoeff-van Gieson staining. Two specimens were scanned using microcomputed tomography (micro-CT), and all scanned images were reconstructed into a three-dimensional model.
At the proximal level of the prostate, the ejaculatory ducts (EDs) and prostatic utricle (PU) together were surrounded by circular smooth-muscle fibers. However, at the seminal colliculus (SC) where the EDs and PU opened, they were mainly surrounded by an abundance of longitudinal fibers. The longitudinal fibers posterior to the EDs and PU formed a distinctive LMC in the posterior urethral wall. In histologic sections and micro-CT images, the LMC extended distally from the level of the SC to the level of the membranous urethra (MBU). We simulated a potential mechanism of LMC using a mathematical model of its movements.
Comprehensive analyses based on in-depth assessment of histologic characteristics and micro-CT images demonstrated extension of the LMC from the level of the SC to the level of the MBU, enabling a better understanding of ejaculation physiology involving the LMC. These results suggest that the LMC in the posterior wall of the PSU is a critical component of ejaculation by facilitating the ejection of seminal vesicle fluid into the PSU via well-coordinated contractions.
前列腺的纵向肌柱（LMC）的形状和功能尚未详细确定。本研究旨在通过研究 LMC 的形态和肌肉排列来阐明前列腺尿道后壁 LMC 在射精排放阶段的作用。
从 14 名韩国成人尸体中获得前列腺和膀胱。使用苏木精和伊红、Masson 三色和Verhoeff-van Gieson 染色对 9 个标本进行组织学分析。使用微计算机断层扫描（micro-CT）对 2 个标本进行扫描，并将所有扫描图像重建为三维模型。
在前列腺的近端水平，射精管（ED）和前列腺囊（PU）一起被圆形平滑肌纤维包围。然而，在 ED 和 PU 开口的精囊球（SC）处，它们主要被大量的纵向纤维包围。ED 和 PU 后面的纵向纤维在后尿道壁形成一个独特的 LMC。在组织学切片和 micro-CT 图像中，LMC 从 SC 水平延伸到膜性尿道（MBU）水平。我们使用其运动的数学模型模拟了 LMC 的潜在机制。
基于对组织学特征和 micro-CT 图像的深入评估的综合分析表明，LMC 从 SC 水平延伸到 MBU 水平，这使我们更好地理解了涉及 LMC 的射精生理学。这些结果表明，PSU 后壁的 LMC 是通过协调收缩将精囊液排入 PSU 来促进射精的关键组成部分。
