Morphometry of the Golgi Apparatus in Developing Liver

Sturgess, Jennifer M.; Iglesia, Felix A. de la

doi:10.1083/jcb.55.2.524

Cited by 37 publications

(11 citation statements)

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“…Since approximately one-third of the Golgi elements of the entire cell population of the liver was probably lost in the first steps of our procedure before the isolation of microsomes (see below), we can estimate that only -.2-3 % of the total protein of the liver is associated with Golgi complexes . The estimate is commensurate with the small relative volume of this cell organ in hepatocytes and agrees well with recently published stereological data (18) which assess at -3% the fractional volume of the Golgi complex in the hepatocytes of the adult rat .…”

Section: Protein Recovery In Golgi Fractionssupporting

confidence: 77%

Golgi Fractions Prepared From Rat Liver Homogenates

Bergeron

Ehrenreich

Siekevitz

et al. 1973

The Journal of Cell Biology

237

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The three Golgi fractions isolated from rat liver homogenates by the procedure given in the companion paper account for 6-7 % of the protein of the total microsomal fraction used as starting preparation . The lightest, most homogeneous Golgi fraction (GFI) lacks typical "microsomal" activities, e .g ., glucose-6-phosphatase, NADPH-cytochrome c-reductase, and cytochrome P-450. The heaviest, most heterogeneous fraction (GF 3 ) is contaminated by endoplasmic reticulum membranes to the extent of -15% of its protein .The three fractions taken together account for nearly all the UDP-galactose :N-acetylglucosamine galactosyltransferase of the parent microsomal fraction, and for -70% of the activity of the original homogenate . Omission of the ethanol treatment of the animals reduces the recovery by half. The transferase activity is associated with the membranes of the Golgi elements, not with their content . Galactose is transferred not only to N-acetylglucosamine but also to an unidentified lipid-soluble component . INTRODUCTION'

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Section: Protein Recovery In Golgi Fractionssupporting

confidence: 77%

Golgi Fractions Prepared From Rat Liver Homogenates

Bergeron

Ehrenreich

Siekevitz

et al. 1973

The Journal of Cell Biology

237

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“…Since quantitative pharmacotoxic changes within hepatocytes can be unequivocably characterized by morphometric methods, these are useful to evaluate the effects of hypolipidemics in several species. Hepatocyte volumes of young rats increase gradually with age until 10 to 16 months following a sudden increase between 3 and 7 weeks of age (29). Such age-related variations markedly influence peroxisomes as well as other cytoplasmic organelles.…”

Section: Discussionmentioning

confidence: 99%

“…Benzene hexachloride (41), dimethrin, phthalates, adipate and sebacate esters (42) are industrial chemicals which produce similar effects, although most likely via different mechanisms from lipid-lowering agents (43), since the peroxisome proliferation to pharmacodynamic activity relationship remains to be established (10,44). Quantitative aspects of hepatocyte architecture have been defined for rats (21,29,(45)(46)(47)(48), but not for dogs, hamsters or monkeys. Since quantitative pharmacotoxic changes within hepatocytes can be unequivocably characterized by morphometric methods, these are useful to evaluate the effects of hypolipidemics in several species.…”

Section: Discussionmentioning

confidence: 99%

“…In order to predict potential adverse reactions, it is important to establish whether or not the peroxisome changes seen in animals can occur in humans, although quantitative microscopic studies on subcellular organelles from human liver are limited. Equivocal changes in peroxisome:mitochondria ratio were reported in a human liver biopsy without full details (l), and in developing human liver, parameters of cell size but no peroxisome indices were presented (29). A series of liver biopsies included Twenty-five-fold increase.…”

Section: Discussionmentioning

confidence: 99%

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Quantitative Microscopy Comparison of Peroxisome Proliferation by the Lipid-Regulating Agent Gemfibrozil in Several Species

Gray

Iglesia

1984

Hepatology

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Peroxisome proliferation, a well-documented subcellular reaction which follows the administration of hypolipidemic agents, has been well studied in rodents. However, quantitative studies of this phenomenon in other species of laboratory animals are not readily available even though these species are commonly used as predictors of tolerance or safety in humans. The quantitative stereologic studies reported here compared the effects of the new hypolipidemic agent gemfibrozil on hepatic peroxisomes of monkeys, dogs, hamsters and rats of both sexes under several treatment schedules. Gemfibrozil was administered to rats at 300 mg per kg per day for 1 year in the diet; to hamsters at 400 mg per kg per day for 2 weeks by diet admixture; to dogs at 300 mg per kg per day in gelatin capsules for 1 year; and to monkeys at 300 mg per kg day for 3 months by gavage. These dose levels were selected on the basis of tolerance from preliminary studies in each species. At the end of each experimental interval, liver samples were processed for quantitative microscopy. Peroxisomes from male rats were enlarged and the number of peroxisomes per cell were increased 7-fold over controls, resulting in a 20-fold increased peroxisome volume per cell. Statistically, significant increases also occurred in female rats and the difference between treated and controls was 3-fold for both number and volume of peroxisomes per cytoplasmic unit volume. In hamsters, peroxisomes were proliferated and were of significantly smaller size to the extent that the volume of cytoplasm occupied by peroxisomes was not significantly changed. In dogs, the number of peroxisomes per cell was increased and the volume fraction was significantly increased in females only. The number of peroxisomes in young monkeys did not change after treatment, and the peroxisome volume was decreased in males and increased in females. Aged monkeys had increased number of peroxisomes per hepatocyte with increased volume fraction. These results indicate significant differences in the magnitude and direction of peroxisome changes, reflecting species-dependent organelle response to hypolipidemic agents. The order of susceptibility of peroxisome proliferation in laboratory animals is dog less than monkey less than hamster less than rat.

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“…In the mature rat liver, the membranes of the Golgi complex occupy approximately 2 to 3% of the cytoplasmic volume, that is roughly 12% of volume reported for the total endoplasmic reticulum, although at earlier stages of development the Golgi complex occupies a much greater proportion of the intracellular membranes, suggesting that it has a role in differentiation (Sturgess & de la Iglesia, 1972).…”

Section: Discussionmentioning

confidence: 86%

The Golgi complex

1973

Self Cite

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The ultrastructural arrangement of membranes of the Golgi complex has been characterized in Golgi fractions isolated from rat liver. Procedures for isolation of these fractions have been modified to provide a good yield of Golgi membranes (60 to 70 %) with greater than 50-fold purification of sialyl transferase, an enzyme specific for the Golgi complex. The isolated membranes appear well preserved and both the dimensions and appearance of the Golgi complex observed by negative staining and in sections of the isolated membranes correlate well with that in liver sections.The Golgi complex consists of a series of plateiike structures, each consisting of a central sac or cisterna from which a network of fine tubules arises. The tubules increase in diameter towards the periphery of the plate and are associated with the formation of vacuoles or secretory vesicles. The structure of the Golgi complex has been related to its role in glycoprotein bfosynthesis.

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Morphometry of the Golgi Apparatus in Developing Liver

Cited by 37 publications

References 11 publications

Golgi Fractions Prepared From Rat Liver Homogenates

Golgi Fractions Prepared From Rat Liver Homogenates

Quantitative Microscopy Comparison of Peroxisome Proliferation by the Lipid-Regulating Agent Gemfibrozil in Several Species

The Golgi complex

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