The synaptic ribbons of the guinea pig pineal gland in sterile, pregnant and fertile but non-pregnant females and in reproductively active males

Me, McNeill; Ds, Whitehead

doi:10.1007/bf01250090

Cited by 12 publications

(2 citation statements)

References 20 publications

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“…The conspicuous arrangement of pinealocytes into follicles or rosettes as recently described in Pirbright White guinea pigs (Jung and Vollrath, 1982) was not found. The ultrastructure of the pineal gland conforms basically to that described in other studies (Lues, 1971;McNeill and Whitehead, 1979). Myelinated and nonmyelinated nerve fibers were found to be particularly abundant in the proximal area (area A) of the gland.…”

Section: Resultssupporting

confidence: 88%

“Synaptic” ribbons and spherules of the guinea pig pineal gland: Inverse day/night differences in number

1983

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The present study deals with the functionally enigmatic "synaptic" ribbons and spherules of guinea pig pinealocytes. Whereas the ribbons have been shown to exhibit a 24-hr rhythmicity with low numbers during the day and high numbers at night, very little of a definitive nature is known about the spherules. Sixteen male guinea pigs of the Hartley strain were perfusion fixed, 8 between 0900-1100 hr, and 8 between 2100-2300 hr. The ribbons and spherules were counted in the pineal parenchyma of the proximal, intermediate, and distal regions. In confirmation of earlier studies, it was found that "synaptic" ribbons are equally abundant in the proximal, intermediate, and distal regions of the gland, during both the day and the night, and that they increase significantly in number at night when compared with daytime values. The spherules, by contrast, are more abundant proximally and are present in greater numbers during the day than at night. As ribbons and spherules are usually not found in one and the same pinealocytic profile, and based on previous electrophysiological studies, it is proposed that the ribbons are morphological markers of nocturnally active pinealocytes, whereas spherules characterize diurnally active pinealocytes.

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Section: Resultssupporting

confidence: 88%

“Synaptic” ribbons and spherules of the guinea pig pineal gland: Inverse day/night differences in number

1983

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“…The most important new finding is that, in contrast to other strains of guinea-pigs (Hiilsernann, 1967;Lues, 1971;McNeill and Whitehead, 1979), large parts of the pineal gland are made up of pinealocytes arranged in rosettes or follicles. Single rosettes have been described in many mammalian species (cf.…”

Section: Discussionmentioning

confidence: 94%

Structural dissimilarities in different regions of the pineal gland of pirbright white guinea-pigs

Jung

Vollrath

1982

J. Neural Transmission

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In the present study, the proximal, intermediate and distal parts of dumbbell-shaped pineal glands of Pirbright White guinea-pigs were investigated with respect to structural dissimilarities. The most conspicuous difference was that while in the proximal part the pinealocytes were arranged in a random fashion, the intermediate and distal regions, except a small ventral area in the latter, exhibited a prominent follicular arrangement of the pinealocytes. Concretions were restricted to the subcapsular region of the intermediate part, whereas cells with hyperchromatic nuclei increased in number in an anterior-posterior direction. In males, pinealocyte nuclear size did not differ significantly in the regions investigated, whereas in females the karyometric results were much more heterogeneous. Exposure of male guinea-pigs to continuous illumination for 45 days resulted in (i) a 25% decrease of pineal volume, the intermediate area being relatively little affected, (ii) an increase in the number of follicles and (iii) a decrease in pinealocyte nuclear size, especially in a ventral zone of the proximal part of the pineal gland.

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The ultrastructure of mammalian pinealocytes: A systematic investigation

Bhatnagar

1992

Microscopy Res & Technique

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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.

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The synaptic ribbons of the guinea pig pineal gland in sterile, pregnant and fertile but non-pregnant females and in reproductively active males

Cited by 12 publications

References 20 publications

“Synaptic” ribbons and spherules of the guinea pig pineal gland: Inverse day/night differences in number

“Synaptic” ribbons and spherules of the guinea pig pineal gland: Inverse day/night differences in number

Structural dissimilarities in different regions of the pineal gland of pirbright white guinea-pigs

The ultrastructure of mammalian pinealocytes: A systematic investigation

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