scispace - formally typeset
Search or ask a question
Journal ArticleDOI

Ultrastructure of the pineal gland in the adult dog.

01 Sep 1988-Journal of Pineal Research (J Pineal Res)-Vol. 5, Iss: 5, pp 479-487
TL;DR: The adult dog pineal gland was studied with the electron microscope and two cell types, pinealocytes and astrocytes, could be identified in pineal parenchyma.
Abstract: The adult dog pineal gland was studied with the electron microscope. Pineal connective tissue spaces were poorly developed and showed capillaries with nonfenestrated endothelial cells. Two cell types, pinealocytes and astrocytes, could be identified in pineal parenchyma. Dog pinealocytes showed microtubules, centrioles, occasional cilia, and well-developed Golgi complexes. These cells showed thin processes with bulbous endings packed with vesicles. Astrocytes were characterized by the presence of numerous filaments. Their processes finished forming a glial layer bordering connective tissue spaces. The presence of myelinated and unmyelinated nerve fibers was also described.
Citations
More filters
Journal ArticleDOI
TL;DR: In the central nervous system of domestic animals, numerous specialized normal structures, unusual cell types, findings of uncertain or no significance, artifacts, and various postmortem alterations can be observed.
Abstract: In the central nervous system (CNS) of domestic animals, numerous specialized normal structures, unusual cell types, findings of uncertain or no significance, artifacts, and various postmortem alterations can be observed. They may cause confusion for inexperienced pathologists and those not specialized in neuropathology, leading to misinterpretations and wrong diagnoses. Alternatively, changes may mask underlying neuropathological processes. "Specialized structures" comprising the hippocampus and the circumventricular organs, including the vascular organ of the lamina terminalis, subfornical organ, subcommissural organ, pineal gland, median eminence/neurohypophyseal complex, choroid plexus, and area postrema, are displayed. Unusual cell types, including cerebellar external germinal cells, CNS progenitor cells, and Kolmer cells, are presented. In addition, some newly recognized cell types as of yet incompletely understood significance and functionality, such as synantocytes and aldynoglia, are introduced and described. Unusual reactive astrocytes in cats, central chromatolysis, neuronal vacuolation, spheroids, spongiosis, satellitosis, melanosis, neuromelanin, lipofuscin, polyglucosan bodies, and psammoma bodies may represent incidental findings of uncertain or no significance and should not be confused with significant microscopic changes. Auto- and heterolysis as well as handling and histotechnological processing may cause postmortem morphological changes of the CNS, including vacuolization, cerebellar conglutination, dark neurons, Buscaino bodies, freezing, and shrinkage artifacts, all of which have to be differentiated from genuine lesions. Postmortem invasion of micro-organisms should not be confused with intravital infections. Awareness of these different changes and their recognition are a prerequisite for identifying genuine lesions and may help to formulate a professional morphological and etiological diagnosis.

38 citations

Journal ArticleDOI
TL;DR: Whereas sufficient structural information now exists on cytoplasmic organelles such as synaptic ribbons and spherules, annulate lamellae, subsurface cisterns, and the several types of synaptic arrangements seen in relation to the pinealocyte soma and its processes, the functional role of these structures in pineal synthetic processes remains to be elucidated.
Abstract: Pinealocytes are not only the principal cellular components of the pineal gland, but they are also the principal synthetic machinery of this enigmatical gland with highly diverse and often questionable empyreal roles assigned to it. Ultrastructural descriptions of pinealocytes belonging to some 70 species of mammals (a mere 2% or less of the over 4,200 mammalian species) have been summarized from the available literature with new observations on 12 species of chiropterans. Space limitation precluded any treatment of the supporting glia, neural elements, and the perivascular spaces. A detailed table lists nearly all mammalian species whose pineal ultrastructure has been investigated. Blanks in this table point to the necessity of studies on those particular groups. A tabular listing of unusual structures reported within the pinealocyte cytoplasm points out the impending experimental work on these species. Such studies using the latest techniques might provide clearer insights into the functional role of the pineal gland as an important and integral component of the neuroendocrine axis. Whereas sufficient structural information now exists on cytoplasmic organelles such as synaptic ribbons and spherules, annulate lamellae, subsurface cisterns, and the several types of synaptic arrangements seen in relation to the pinealocyte soma and its processes, the functional role of these structures in pineal synthetic processes remains to be elucidated.

31 citations

Journal ArticleDOI
TL;DR: The expression of glial antigens vimentin (VIM) and glial fibrillary acidic protein (GFAP) is described in the pineal gland of cats and dogs from the first postnatal days to adulthood.
Abstract: The expression of glial antigens vimentin (VIM) and glial fibrillary acidic protein (GFAP) is described in the pineal gland of cats and dogs from the first postnatal days to adulthood. VIM immunopositive cells were observed from the first postnatal days in both species. GFAP expression starts from the second postnatal week. In adults, a notable population of stellate cells immunopositive for GFAP and VIM was found dispersed throughout the gland. According to their immunocytochemical profile, these cells could be identified as astrocytes.

29 citations

Journal ArticleDOI
TL;DR: Cat pinealocytes showed a nucleus with prominent nucleoli, a well developed Golgi apparatus, centrioles, granular endoplasmic reticulum, ribosomes, abundant microtubuli and enlarged mitochondria and their processes were characterized by the presence of abundant filaments.
Abstract: The ultrastructure of the pineal gland in the adult cat is described and compared with that of other mammals. Connective tissue spaces showed capillaries with nonfenestrated endothelia and numerous unmyelinated nerve fibers. In the proximal region of the gland, myelinated nerve fibers coming from the anterior commissure were also found. Cat pinealocytes showed a nucleus with prominent nucleoli, a well developed Golgi apparatus, centrioles, granular endoplasmic reticulum, ribosomes, abundant microtubuli and enlarged mitochondria. Pinealocytes showed several long processes with bulbous endings filled with clear vesicles and scarce "synaptic" ribbons. Pineal astrocytes and their processes were characterized by the presence of abundant filaments.

29 citations

Journal ArticleDOI
TL;DR: In the course of ovine intrauterine development, the vascular affinity of this second cell population, composed of glial‐like or astrocytic cells at varying stages of maturity, leads to the formation of a limiting pineal barrier which may constitute the morphological expression of a hypothetical functional involvement in the exchange of substances between blood and pineal parenchyma.
Abstract: Ultrastructural and immunohistochemical techniques were used to study the second cell type in sheep embryo pineal glands. Thirty-two embryos were studied from day 54 of development through birth. Specimens were arranged in four age groups, defined in terms of the most relevant histological features: Group 1 (54-67 days of prenatal development), Group 2 (71-92 days), Group 3 (98-113 days), and Group 4 (118-150 days). At 98 days, a second cell type was observed which differed from pinealoblasts and showed uniform ultrastructural characteristics similar to those of astrocytes in the central nervous system. Ultrastructural homogeneity was not matched by the results of histochemical and immunohistochemical analysis: while all Type II cells stained positive to phosphotungstic acid hematoxylin, only 50% expressed glial fibrillary acidic protein. In the course of ovine intrauterine development, the vascular affinity of this second cell population, composed of glial-like or astrocytic cells at varying stages of maturity, leads to the formation of a limiting pineal barrier. This barrier may constitute the morphological expression of a hypothetical functional involvement in the exchange of substances between blood and pineal parenchyma.

23 citations

References
More filters
Book ChapterDOI
TL;DR: This chapter presents an electron-microscopic study of the epiphyseal cell and its histological disposition with an emphasis on the morphological evidence of secretion.
Abstract: This chapter presents an electron-microscopic study of the epiphyseal cell and its histological disposition with an emphasis on the morphological evidence of secretion. Detection of histological design in the pineal body is complicated by divergent results of fixation by immersion and perfusion. Cytological preservation is suboptimal, following immersion fixation, and it is indicated by the vesiculation of cytoplasmic membranes, the extraction of lipid droplets, the appearance of nuclear inclusions, and the slight swelling of the cells without conspicuous dilution of their cytoplasm. Such subtle swelling generates an artifactitious histological compactness resembling the texture of a gland or epithelioid body. Fixation of the epiphysis by intravascular perfusion yields the best cytoplasmic preservation, even when accompanied by a variable widening of the clefts between epiphyseal cells and the diminution of amorphous interstitial material, a phenomenon that occurs chiefly in the central portion of the pineal body.

232 citations

Journal ArticleDOI
TL;DR: The presence of the glial marker proteins, the S-100 and theglial fibrillary acidic (GFA) protein, in the pineal gland was investigated in the rat and indicates that the interstitial cells are of neuroectodermal origin, possibly macroglial cells themselves.

196 citations


"Ultrastructure of the pineal gland ..." refers background in this paper

  • ...Glial cells have also been identified in mammalian pineal gland by using immunohistochemical techniques for astrocyte antigenic markers [Moller et al., 1978; Lowenthal et al., 1982; Huang et al., 1984; Schachner et al., 1984; Cozzi, 1986]....

    [...]

Journal ArticleDOI
TL;DR: It is suggested that the pinealocytes of the neonatal rat undergo "photoreceptor-like" differentiation during a transient neonatal period, which may provide an explanation for light-induced biochemical changes described in neonatal rats whose eyes had been enucleated.
Abstract: The pineal body and the retina of the neonatal Sprague-Dawley rat were studied by light and electron microscopy, and the morphologic differentiation of the parenchymal cells of the pineal body was compared with that of the developing photoreceptor cells of the retina. Between the ages of 4 and 12 days after birth, some of the developing pinealocytes were observed to become elongated and polarized, with their nuclei located at one pole. "Synaptic" ribbons were observed within the cell body. At the opposite pole the cells developed elongated cell processes that initially contained microtubules and ribosomes. These cell processes projected into luminal spaces and were attached by structures resembling zonulae adherentes to the adjacent cells. Extending from the tips of the cell processes, cilia with a 9 + 0 arrangement were observed. Lamellated and vesicular membranes were noted at the tips of the cilia. Such morphologic differentiation, however, could be observed only in rats younger than 17 days. Comparison of the morphologic features of the neonatal pinealocytes with those of the developing retinal photoreceptor cells showed much similarity. It is suggested that the pinealocytes of the neonatal rat undergo "photoreceptor-like" differentiation during a transient neonatal period. Such morphologic differentiation may provide an explanation for light-induced biochemical changes described in neonatal rats whose eyes had been enucleated.

118 citations


"Ultrastructure of the pineal gland ..." refers background in this paper

  • ...In other marrunals, both organelles can be seen during fetal [Clabough, 1973; Calvo and Boya, 1981] and neonatal period [Zimmerman and Tso, 1975; Calvo and Boya, 1983]....

    [...]

Book ChapterDOI
TL;DR: In the light of the different concepts treated, the confused state of comprehension of pineal functions becomes more understandable and most of the paradoxical and contradictory facts related to pineal function become less confusing.
Abstract: Publisher Summary In various recent reviews it has been concluded that the pineal body synthesizes a number of compounds and is an endocrine gland whose secretory products influence the development and function of the reproductive organs. It has been postulated that the pineal mediates certain environmental factors which regulate the function of the reproductive system. At present, no known pineal compound satisfies all of the classical criteria for a candidate hormone, that is, a substance produced exclusively in the pineal gland and having a specific functional influence on (a) distant target organ(s). In the light of the different concepts treated, the confused state of comprehension of pineal functions becomes more understandable. Only chemical identification of the different hormones synthesized in the pineal will permit the exact determination of pineal function. It is evident that one must think in terms of multiplicity of types of regulation in relation to the multiplicity of effects. Probably, the mammalian pineal gland is a synchronizer contributing to seasonal and probably also to circadian organization of functions. It is nonexclusively involved in different neuroendocrine mechanisms, which attunes the physiological adaptation of animals to their unique daily and annual patterns. When considering these points, most of the paradoxical and contradictory facts related to pineal function become less confusing.

108 citations


"Ultrastructure of the pineal gland ..." refers background in this paper

  • ...…functionally important cell structures such as granular vesicles, subsurface cisterns, bulbous endings packed with vesicles, and synaptic ribbons [Pevet, 1979; Vollrath, 1981]' Nevertheless, other cellular organelles (lipid droplets, annulate lamellae, proteinaceous material in cisterns of…...

    [...]

Book
13 Mar 1967

101 citations


"Ultrastructure of the pineal gland ..." refers background in this paper

  • ...In other marnmals, the nucleus of the pinealocyte has deep infoldings of its nuclear envelope, lacks peripheral heterochromatin, and exhibit large nucleoli [Ander son, 1965;Wolfe, 1965; Arstila, 1967;CalvoandBoya, 1983, 1984;Cozzi, 1986]....

    [...]

  • ...Lipid droplets are frequent in marnmal pinealocytes [VoUrath, 1981; Dog Pineal llitrastructure 485 Karasek, 1983] and especially abundant in the rat pinealocytes [Wolfe, 1965; Arstila, 1967; Calvo and Boya, 1984]....

    [...]