Oda Y, Nakanishi I
Department of Pathology, School of Medicine, Kanazawa University, Ishikawa, Japan.
J Comp Neurol. 1987 Sep 8;263(2):282-9. doi: 10.1002/cne.902630210.
The developmental changes of the fourth ventricular roof of the brain in mouse fetuses and neonates were observed by scanning and transmission electron microscopy with particular attention to the caudal portion where a median foramen might be formed during the fetal period. The fourth ventricular roof was continuously paved with a single layer of cuboidal or squamous neuroepithelial cells with poorly developed basement membrane until the 12th intrauterine day when the primitive choroid plexus appeared at the middle portion of the roof. With development of the choroid plexus, the roof caudal to the choroid plexus (membranous roof) became thinner, and it was mostly lined with a single layer of flat ependymal cells having cilia and microvilli and resting on a continuous basement membrane. These ependymal cells were connected with one another by a gap junction or an intermediate junction for the entire period examined, except at the 13th to 14th intrauterine days, during which the interependymal clefts were transiently widened up to 2 microns in width, in places, without disruption of the continuous basement membrane. Neither a median aperture nor wide intercellular pores were formed in the membranous roof during the fetal or neonatal term.
通过扫描电子显微镜和透射电子显微镜观察了小鼠胎儿和新生儿脑第四脑室顶的发育变化，特别关注胎儿期可能形成正中孔的尾部区域。直到子宫内第12天原始脉络丛出现在脑室顶中部之前，第四脑室顶一直由单层立方或扁平神经上皮细胞覆盖，基底膜发育不良。随着脉络丛的发育，脉络丛尾侧的脑室顶（膜性顶）变薄，主要由单层具有纤毛和微绒毛的扁平室管膜细胞内衬，这些细胞位于连续的基底膜上。在整个检查期间，这些室管膜细胞通过缝隙连接或中间连接相互连接，但在子宫内第13至14天除外，在此期间，室管膜间裂在某些部位短暂增宽至2微米，而连续的基底膜未被破坏。在胎儿期或新生儿期，膜性顶均未形成正中孔或宽大的细胞间孔隙。
