Haddad A, Laicine E M, Tripathi B J, Tripathi R C
Departamento de Biologia Celular e Molecular e Bioagentes Patogênicos, Faculdade de Medicina de Ribeirão Preto, USP, Brazil.
Exp Eye Res. 2001 Sep;73(3):345-53. doi: 10.1006/exer.2001.1042.
We investigated the structural organization of the choroid especially with regard to the presence of extravascular smooth muscle (EVSM) cells in albino rabbits. The eyes were fixed by intracardiac perfusion and processed for light, confocal, and electron microscopy. An unlabeled monoclonal antibody against alpha-actin of smooth muscle and a horseradish-peroxidase-conjugated secondary antibody were used for immunodetection of smooth muscle actin by light microscopy. For confocal microscopy, whole mount choroids were immunostained with a fluorescein isothiocyanate-conjugated (FITC) antibody. Our investigations revealed that the choroidal vessels are enveloped by bundles of EVSM. In contrast to the circular orientation of the smooth muscle cells of the tunica media of the choroidal vessels, the cells of the EVSM system were oriented longitudinally along the external surface of the vessel wall. The EVSM cells were strongly immunopositive for smooth muscle alpha-actin and exhibited a green fluorescence of the FITC-labeled anti-alpha-actin antibody. Individual cells were elongated and spindle-shaped, had the usual ultrastructural features of smooth muscle cells and, in places, were organized as 20 layers. EVSM cells were present throughout the thickness of the choroid, but not between the fenestrated endothelial lining of the choriocapillaris and Bruch's membrane, and extended from the optic nerve to the ciliary body where they merged with the ciliary muscles. Based on the three dimensional organization, immunoreactivity, and cellular and subcellular features of the EVSM system as well as information in the literature, we hypothesize that, functionally, this system, in conjunction with the choroidal vasculature, contributes to the myogenic control of choroidal blood flow and tissue volume, and also affects the intraocular pressure as well as the refractive and accommodative state of the eye.
我们研究了白化兔脉络膜的结构组织，特别是关于血管外平滑肌（EVSM）细胞的存在情况。通过心脏内灌注固定眼睛，并进行光镜、共聚焦显微镜和电子显微镜检查。使用抗平滑肌α-肌动蛋白的未标记单克隆抗体和辣根过氧化物酶偶联的二抗，通过光镜免疫检测平滑肌肌动蛋白。对于共聚焦显微镜检查，用异硫氰酸荧光素偶联（FITC）抗体对全层脉络膜进行免疫染色。我们的研究表明，脉络膜血管被EVSM束包裹。与脉络膜血管中膜平滑肌细胞的环形排列不同，EVSM系统的细胞沿血管壁外表面纵向排列。EVSM细胞对平滑肌α-肌动蛋白呈强免疫阳性，并表现出FITC标记的抗α-肌动蛋白抗体的绿色荧光。单个细胞细长且呈纺锤形，具有平滑肌细胞通常的超微结构特征，并且在某些部位组织成20层。EVSM细胞存在于脉络膜的整个厚度中，但不存在于脉络膜毛细血管的有窗孔内皮衬里和布鲁赫膜之间，并且从视神经延伸到睫状体，在那里它们与睫状肌融合。基于EVSM系统的三维组织结构、免疫反应性以及细胞和亚细胞特征，以及文献中的信息，我们假设，在功能上，该系统与脉络膜血管系统一起，有助于对脉络膜血流和组织体积进行肌源性控制，并且还影响眼内压以及眼睛的屈光和调节状态。
