位於第三腦室頂端的連合下器官(Subcommissural Organ)是由特殊的室管膜細胞所組成。由過去的實驗顯示被認為與滲透調節有關。由於倉鼠與沙鼠同為沙漠型動物且有保存水份的能力，因此我們預期，在倉鼠與沙鼠的連合下器官表面微細構造應存在著明顯的種類差異。在本次實驗中，我們是使用掃瞄式電子顯微鏡來觀察表面微細構造的。在低倍掃瞄式電子顯微鏡下，階梯狀繞摺只存在於倉鼠，而不見於沙鼠；反之，縱向摺疊則僅見於沙鼠連合下器官之喙部，在倉鼠則無。在高倍掃瞄式電子顯微鏡下，倉鼠與沙鼠的連合下器官之室管膜細胞，自喙部至尾部均顯現明顯的區域性變異。然而、兩種動物的室管膜細胞也有其相同之處：(1)游離的細胞表面具有頂端突出物，(2)頂端突出物具有球狀結構、無數的微絨毛及單一或成雙的纖毛，(3)有疑似雷斯納氏纖維(Reissner’s fiber)的絲狀物質附著於游離表面。
The subcommissural organ (SCO), located on the roof the 3rd ventricle and comprised of highly specialized ependymal cells, is a shared feature of many species. Earlier experiments have suggested that SCO is involved in osmotic regulation, though reference to the secretory function of ependymal sells or interspecies structural variations was not verified. In order to provide further research, SCO samples from hamsters and gerbils were compared with specific attention to surface morphology. The original habitat of both rodents is the desert, and both exhibit an extraordinary capacity to retain water. This paper presents results of that study. Overall morphology and fine surface structure of respective specimens was analyzed by scanning electron microscopy (SEM). Under lower power SEM, ladder-like flexures were clearly observed in hamster SCO, while longitudinal folds were visible in the rostral section of gerbil samples. Higher magnification showed regional variation in ependymal cells in samples from both taken from the rostral to caudal SCO sections. Individual ependymal cells of gerbils and hamsters shared similar characteristics: (1) apical protrusion into the ventricular cavity, (2) bulbous structures, numerous microvilli, and either solitary or double cilia on the apical protrusion, and (3) a fibrous mesh-like material (Reissner’s fiber) covering the cavity.
