Publication: Cell populations in the pineal gland of the viscacha (Lagostomus maximus). Seasonal variations
Authors
Cernuda-Cernuda, R. ; Piezzi, R.S. ; Domínguez, S. ; Alvarez-Uría, M.
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Publisher
Murcia : F. Hernández
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DOI
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info:eu-repo/semantics/article
Description
Abstract
Pineal samples of the viscacha, which were
taken in winter and in summer, were analysed using both
light and electron microscopy. The differences found
between the two seasons were few in number but
significant. The parenchyma showed two main cell
populations. Type I cells occupied the largest volume of
the pineal and showed the characteristics of typical
pinealocytes. Many processes, some of which were filled
with vesicles, could be seen in intimate contact with the
neighbouring cells. The presence in the winter samples
of “synaptic” ribbons and spherules, which were almost
absent in the summer pineals, suggests a seasonal
rhythm. These synaptic-like structures, as well as the
abundant subsurface cisterns present in type I cells,
appeared as basic differential features which allowed
these cells to be distinguished from type II cells. These
latter cells, which can be classified as interstitial cells,
showed some other distinguishing features, such as
irregular-shaped nuclei, abundant deposits of glycogenlike
particles and structures of unknown function
consisting of concentric cisterns surrounding a dense
body. In the summer, interstitial cells displayed
numerous large round bodies, which contributed to
increase the cellular volume slightly. Regarding other
constituents, like glial cell processes, vessels of nonfenestrated
endothelium and sympathetic innervation, no
qualitative differences were observed between the two
seasons studied.
We have presented here some morphological evidences of the circannual rhythm of the viscacha
pineal, as well as ultrastructural criteria for
distinguishing the main cell populations of this organ,
which could be useful for studies carried out in other
mammals.
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