Oda Y, Nakanishi I
J Comp Neurol. 1987 Feb 8;256(2):299-307. doi: 10.1002/cne.902560209.
A scanning and transmission electron microscopic study was done of the caudal portion of the fourth ventricular roof in the adult mouse. The caudal portion of the fourth ventricular roof was divided into two parts: choroid plexus and nonchoroid plexus roof. The plexus epithelial cells had numerous microvilli and were connected with each other with a tight junction, gap junction, or zonula adherens. The nonchoroid plexus roof was a thin neuroglial membrane with a continuous basement membrane, which we designated as "the membranous roof." The membranous roof was mostly composed of a single layer of paving ependymal cells supported by discontinuous pial cells. The ependymal cells were characterized by their squamous cell configuration, various numbers of microvilli and cilia, and a continuous basement membrane. They were connected with each other by gap junctions or zonulae adherentes, but they lacked tight junctions. Neither a cytoplasmic pore nor a wide intercellular cleft was identified. Neuronal and glial cell processes were occasionally observed. The aperture that is supposed to exist in the caudal, median portion of the fourth ventricular roof of the adult mammalian brains, called the foramen of Magendie in the human brain, was not found. Our observations suggest that the membranous roof itself would permit passage of the cerebrospinal fluid containing macromolecules via the interependymal cell clefts, implying that the foramen of Magendie would not be an anatomical aperture but a functional channel for the outflow of the cerebrospinal fluid.
对成年小鼠第四脑室顶的尾部进行了扫描电镜和透射电镜研究。第四脑室顶的尾部被分为两部分：脉络丛和非脉络丛顶。脉络丛上皮细胞有许多微绒毛，通过紧密连接、缝隙连接或黏着小带相互连接。非脉络丛顶是一层薄的神经胶质膜，有连续的基底膜，我们将其称为“膜性顶”。膜性顶主要由单层扁平室管膜细胞组成，由不连续的软膜细胞支撑。室管膜细胞的特征是其鳞状细胞形态、数量各异的微绒毛和纤毛以及连续的基底膜。它们通过缝隙连接或黏着小带相互连接，但缺乏紧密连接。未发现细胞质孔或宽大的细胞间裂隙。偶尔可观察到神经元和胶质细胞的突起。在成年哺乳动物脑第四脑室顶尾部中间部分应存在的孔，在人脑中称为马让迪孔，未被发现。我们的观察结果表明，膜性顶本身可允许含有大分子的脑脊液通过室管膜细胞间裂隙，这意味着马让迪孔不是一个解剖学上的孔，而是脑脊液流出的功能性通道。
