Summary
The pineal gland in the possum is represented by a thickening in the wall of the pineal recess. A superficial pineal body and a pineal stalk are characteristically lacking.
The ependyma related to the gland is specialized but differs markedly from the lining in other circumventricular organs in form and in surface morphology. Two distinct topographic zones have been recognized. In the middle is a mass of cells which form a prominent knobby-surfaced central zone. These cells are characterized by the absence of cilia, the paucity of microvilli and blebs and the presence of processes which overlap adjacent cells. A surface pattern formed of cell outlines was lacking. It is suggested that the central zone is lined by pinealocytes, supporting cells and the processes of both cell types. Most of the central zone is surrounded by an intermediate zone of variable width. The latter region has been observed to possess a circumventricular organ-type surface morphology. It is sparsely ciliated, almost totally covered by a carpet of microvilli and it exhibits a variety of surface specializations. Supraependymal cells and various transitory supraependymal cell processes are also present.
Outside the specialized ependyma is the peripheral zone which like the regular ventricular lining is densely ciliated. Supraependymal processes are found among the clusters of cilia, or rarely, on the surface of the ciliary bed.
Season and sex related differences in surface ultrastructure were not observed.
Similar content being viewed by others
References
Card JP, Mitchell JA (1978) Scanning electron microscopic observations of supraependymal elements overlying the organum vasculosum of the lamina terminalis of the hamster. In: Becker RP, Johari O (eds) Scanning electron microscopy Vol II. SEM Inc., Illinois, p 803
Clark JM, Glagov S (1976) Evaluation and publication of scanning electron micrographs. Science 192:1360–1361
Coates PW (1973) Supraependymal cells in recesses of monkey third ventricle. Am J Anat 136:533–539
Coates PW (1975) Scanning electron microscopy of a second type of supraependymal cell in the monkey third ventricle. Anat Rec 182:275–288
Delahunt B (1975) Studies on the pineal gland. A light and electron microscopic study of the pineal gland of the brush-tailed possum (Trichosurus vulpecula). B Med Sc Thesis. University of Otago, Dunedin
Delahunt B, Trotter WD, Samarasinghe DD (1975) The morphology of the pineal recess of the brush-tailed possum (Trichosurus vulpecula). Proc Univ Otago Med Sch 53:63–64
Dellmann H-D, Linner JG (1977) Correlative light, scanning and transmission electron microscopy of the ventricular surface of the rat subfornical organ with special emphasis on supraependymal cells. Anat Rec 187:565
Gregorek JC, Seibel HR, Reiter RJ (1977) The pineal complex and its relationship to other epithalamic structures. Acta Anat 99:425–434
Hartwig HG, Korf HW (1978) The epiphysis cerebri of poikilothermic vertebrates: A photosensitive neuroendocrine circumventricular organ. In: Becker RP, Johari O (eds) Scanning electron microscopy Vol II. SEM Inc., Illinois, p 163
Hewing M (1978) A liquor contacting area in the pineal recess of the golden hamster (Mesocricetus auratus). Anat Embryol 153:295–304
Hofer H (1958) Zur Morphologie der circumventrikulären Organe des Zwischenhirns der Säugetiere. Deutsch Zool Ges Verhandl 8:202–251
Jordan HE (1911) The microscopic anatomy of the epiphysis of the opossum. Anat Rec 5:325–338
Kappers Ariëns J (1960) The development, topographical relations and innervation of the epiphysis cerebri in the albino rat. Z Zellforsch 52:163–215
Kenny GCT, Scheelings FT (1979) Observations of the pineal region of non-eutherian mammals. Cell Tissue Res 198:309–324
Krapp C (1978) The ependyma on the pineal of the guinea pig (Cavia cobaya). A scanning electron microscopic investigation. Anat Embryol 152:217–222
Leonhardt H, Lindemann B (1973a) Surface morphology of the subfornical organ in the rabbit's brain. Z Zellforsch 146:243–260
Leonhardt H, Lindemann B (1973b) Über ein supraependymales Nervenzell-, Axon- und Gliazell- system. Eine raster- und transmissionselektronenmikroskopische Untersuchung am IV. Ventrikel (Apertura lateralis) des Kaninchengehirns. Z Zellforsch 139:285–302
Martinez-Martinez P, de Weerd H (1977) The fine structure of the ependymal surface of the recessus infundibularis in the rat. Anat Embryol 151:241–265
Mestres P (1978) Old and new concepts about circumventricular organs. An overview. In: Becker RP, Johari O (eds) Scanning electron microscopy Vol II. SEM Inc., Illinois, p 137
Mitchell JA, Card JP (1978) Supraependymal neurons overlying the periventricular region of the third ventricle of the guinea pig: A correlative scanning-transmission electron microscopic study. Anat Rec 192:441–458
Oksche A (1965) Survey of the development and comparative morphology of the pineal organ. Prog Brain Res 10:3–29
Paull WK, Scott DE, Boldosser WG (1974) A cluster of supraependymal neurons located within the infundibular recess of the rat third ventricle. Am J Anat 140:129–133
Paull WK, Martin H, Scott DE (1977) Scanning electron microscopy of the third ventricular floor of the rat. J Comp Neurol 175:301–310
Quay WB (1965) Histological structure and cytology of the pineal organ in birds and mammals. Prog Brain Res 10:49–86
Ribas JL (1977) The rat epithalamus. I. Correlative scanning-transmission electron microscopy of supraependymal nerves. Cell Tissue Res 182:1–16
Samarasinghe DD (1980) An ultrastructural study of possible secretory routes in the pineal organ of the brush-tailed possum (Trichosurus vulpecula). J Anat 130:201
Scott DE, Krobisch-Dudley G, Paull WK, Kozlowski G (1977) The ventricular system in neuroendocrine mechanisms. III. Supraependymal neuronal networks in the primate brain. Cell Tissue Res 179:235–254
Sheridan MN, Reiter RJ (1970) Observations on the pineal system in the hamster. I. Relations of the superficial and deep pineal to the epithalamus. J Morphol 131:153–162
Tulsi RS (1977) Scanning electron microscopy of the pineal recess of the adult Trichosurus vulpecula. J Anat 124:515
Tulsi RS (1979) A scanning electron microscope study of the pineal recess of the adult brush-tailed possum (Trichosurus vulpecula). J Anat 129:521–530
Vollrath L (1979) Comparative morphology of the vertebrate pineal complex. Prog Brain Res 52:25–38
Weindl A (1973) Neuroendocrine aspects of circumventricular organs. In: Ganong WF, Martini L (eds) Frontiers in neuroendocrinology. Oxford UP, New York, p. 3
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Samarasinghe, D., Delahunt, B. The ependyma of the saccular pineal gland in the non-eutherian mammal Trichosurus vulpecula . Cell Tissue Res. 213, 417–432 (1980). https://doi.org/10.1007/BF00237888
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00237888