Summary
Peculiar cells forming cysts were observed in the area postrema and sometimes also in the choroid plexus and the tela chorioidea near the area postrema, and were studied in detail by electron microscopy. The cytological features of the cyst cell and its junctional relationship to neighboring cells imply that cyst cells are derived from ependymal and choroid epithelial cells. The cyst cells usually contact directly the perivascular spaces of postremal, choroidal or pial capillaries, where the cytoplasm is often considerably attenuated. The cystic lumen is commonly filled with a flocculent material. The limiting membrane of the cystic lumen, which frequently bears cilia and microvilli, has the same thickness as the surface cell membrane. In many cases, the cyst is surrounded by the cytoplasm of a single cell. In some cases, however, two cells participate in the formation of the cyst, although one is only a slender process and joined by a zonula occludens with the main cyst cell. Horseradish peroxidase (HRP) injected into the cerebrospinal fluid (CSF) space failed to enter the cystic lumen. A possible significance of the cyst in relation to the CSF and blood circulation was considered.
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References
Andres KH (1965) Der Feinbau des Subfornikalorganes vom Hund. Z Zellforsch 68:445–473
Angevine JB (1975) The nervous tissue. In: Bloom W, Fawcett DW eds, A textbook of histology (10th ed.). WB Saunders Co, Philadelphia-London-Toronto
Bodoky M, Koritsánszky S, Réthelyi M (1979) A system of intraependymal cisternae along the margins of the median eminence in the rat: structure, three-dimensional arrangement and ontogeny. Cell Tissue Res 196:163–173
Borison HL (1974) Area postrema: chemoreceptor trigger zone for vomiting — is that all? Life Sci 14:1807–1817
Broadwell RD, Brightman MW (1976) Entry of peroxidase into neurons of the central and peripheral nervous systems from extracerebral and cerebral blood. J Comp Neurol 166:257–284
Cammermeyer J (1973) Hypependymal cysts adjacent to and over circumventricular regions in primates. Acta Anat 84:353–373
Gotow T, Hashimoto PH (1979) Fine structure of the ependyma and intercellular junctions in the area postrema of the rat. Cell Tissue Res 201:207–225
Hashimoto PH, Hama K (1968) An electron microscope study on protein uptake into brain regions devoid of the blood-brain barrier. Med J Osaka Univ. 18:331–346
Hirano A, Zimmermann HM, Levine S (1966) The fine structure of cerebral fluid accumulation: reactions of ependyma to implantation of cryptococcal polysaccharide. J Pathol Bact 91:149–155
Klara PM, Brizzee KR (1975) The ultrastructural morphology of the squirrel monkey area postrema. Cell Tissue Res 160:315–326
Klara PM, Brizzee KR (1977a) Ultrastructure of the feline area postrema. J Comp Neurol 171:409–432
Klara PM, Brizzee KR (1977b) Tancytic ependyma in the mammalian IV ventricle. Anat Rec 187:626
Klara PM, Brizzee KR, Chen I-Li, Yates RD (1978) Ultrastructural localization of ATPase activity in the dog area postrema. Brain Res 146:165–171
Leslie RA, Gwyn DG, Morrison CM (1978) The fine structure of the ventricular surface of the area postrema of the cat, with particular reference to supraependymal structures. Am J Anat 153:273–290
Milhorat TH (1975) The third circulation revisited. J Neurosurg 42:628–645
Page RB, Rosenstein JM, Dovey BJ, Leure-duPree AE (1979) Ependymal changes in experimental hydrocephalus. Anat Rec 194:83–104
Papacharalampous NX, Schwink A, Wetzstein R (1968) Elektronenmikroskopische Untersuchungen am Subcommissuralorgan des Meerschweinchens. Z Zellforsch 90:202–229
Pollay M (1975) Formation of cerebrospinal fluid. Relation of studies of isolated choroid plexus to the standing gradient hypothesis. J Neurosurg 42:665–673
Rivera-Pomar JM (1966) Die Ultrastruktur der Kapillaren in der Area postrema der Katze. Z Zellforsch 75:542–554
Rodriguez EM (1969) Ependymal specializations. I. Fine structure of the neural (internal) region of the toad median eminence, with particular reference to the connections between the ependymal cells and the subependymal capillary loops. Z Zellforsch 102:153–171
Rohrschneider I, Schinko I, Wetzstein R (1972) Der Feinbau der Area postrema der Maus. Z Zellforsch 123:251–276
Rudert H, Schwink A, Wetzstein R (1968) Die Feinstruktur des Subfornikalorgans beim Kaninchen. II. Das neuronale und gliale Gewebe. Z Zellforsch 88:145–179
Sahar A (1972) The effect of pressure on the production of cerebrospinal fluid by the choroid plexus. J Neurol Sci 16:49–58
Scott DE, Knigge KM (1970) Ultrastructural changes in the median eminence of the rat following deafferentation of the basal hypothalamus. Z Zellforsch 105:1–32
Shimizu N, Ishii S (1964) Fine structure of the area postrema of the rabbit brain. Z Zellforsch 64:462–473
Špaček J, Pařízek J (1969) The fine structure of the area postrema of the rat. Acta Morphol Acad Sci Hung 17:17–34
Stumpf WE, Hellreich MA, Aumüller G, Lamb IV JC, Sar M (1977) The collicular recess organ: evidence for structural and secretory specialization of the ventricular lining in the collicular recess. Cell Tissue Res 184:29–44
Weindl A (1965) Zur Morphologie und Histochemie von Subfornicalorgan, Organum vasculosum laminae terminalis und Area postrema bei Kaninchen und Ratte. Z Zellforsch 67:740–775
Weindl A, Joynt RJ (1972) Ultrastructure of the ventricular walls. Arch Neurol 26:420–427
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Gotow, T., Hashimoto, P.H. Fine structure of ependymal cysts in and around the area postrema of the rat. Cell Tissue Res. 206, 303–318 (1980). https://doi.org/10.1007/BF00232774
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DOI: https://doi.org/10.1007/BF00232774