The pinealocyte nucleolus

Lew, G.M.; Payer, Andrew F.; Quay, W. B.

doi:10.1007/bf00217279

Cited by 10 publications

(1 citation statement)

References 19 publications

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“…The electron-dense core of mature granules is routinely [41], but not always, observed, perhaps in some cases because of difficulty in fixation [26] and in others because mature granules might possess luminal activities that cause disintegration of the core [42]. In addition, the sizes of immature granules (IGs) and mature granules tend to be altered following pharmcological secretagogue stimulation, resulting in subnormal-sized IGs [25,43] or supranormal-sized IGs [26,44]. Nevertheless, under physiological conditions, condensing vacuoles are generally larger than, or of comparable size to, the mature granules [45][46][47].…”

Section: Introductionmentioning

confidence: 99%

Sorting and storage during secretory granule biogenesis: looking backward and looking forward

Arvan

Castle

1998

Biochemical Journal

483

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Secretory granules are specialized intracellular organelles that serve as a storage pool for selected secretory products. The exocytosis of secretory granules is markedly amplified under physiologically stimulated conditions. While granules have been recognized as post-Golgi carriers for almost 40 years, the molecular mechanisms involved in their formation from the trans-Golgi network are only beginning to be defined. This review summarizes and evaluates current information about how secretory proteins are thought to be sorted for the regulated secretory pathway and how these activities are positioned with respect to other post-Golgi sorting events that must occur in parallel. In the first half of the review, the emerging role of immature secretory granules in protein sorting is highlighted. The second half of the review summarizes what is known about the composition of granule membranes. The numerous similarities and relatively limited differences identified between granule membranes and other vesicular carriers that convey products to and from the plasmalemma, serve as a basis for examining how granule membrane composition might be established and how its unique functions interface with general post-Golgi membrane traffic. Studies of granule formation in vitro offer additional new insights, but also important challenges for future efforts to understand how regulated secretory pathways are constructed and maintained.

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Section: Introductionmentioning

confidence: 99%

Sorting and storage during secretory granule biogenesis: looking backward and looking forward

Arvan

Castle

1998

Biochemical Journal

483

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Morphometric analysis of the pineal complex of the golden hamster over a 24‐hour light: Dark cycle: I. The superficial pineal in untreated and optically enucleated animals

Dombrowski

McNulty

1984

Am. J. Anat.

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Morphometric analysis of the superficial pineal gland of intact and blinded golden hamsters was conducted at both the light and electron microscopic level. The volume of the superficial gland was estimated to be 151 X 10(6) micron 3, comprising 90-94% of the total pineal parenchymal tissue. Analysis of structural rhythms in animals maintained under a 14:10 L:D cycle showed significant 24-hr variations in values for pinealocyte nuclei, nucleoli, rough and smooth endoplasmic reticulum, Golgi bodies, dense bodies, and dense-cored vesicles. Peak values for these structures generally occurred at the light:dark interface. These results provide morphological correlates for known rhythmic variations in the synthesis of pineal-gland products. Superficial pineals examined 8 weeks following optic enucleation exhibited a decrease in the volume of pinealocyte nuclei and cytoplasm, while nucleolar size and the amounts of smooth and rough endoplasmic reticulum, Golgi bodies, dense bodies and dense-cored vesicles were enhanced. The latter changes are interpreted as indications of increased synthetic activity by the superficial pineal gland in response to light deprivation.

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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 pinealocyte nucleolus

Cited by 10 publications

References 19 publications

Sorting and storage during secretory granule biogenesis: looking backward and looking forward

Sorting and storage during secretory granule biogenesis: looking backward and looking forward

Morphometric analysis of the pineal complex of the golden hamster over a 24‐hour light: Dark cycle: I. The superficial pineal in untreated and optically enucleated animals

The ultrastructure of mammalian pinealocytes: A systematic investigation

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