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G E PALADE

Publications and source records attributed to G E PALADE.

48 records · Page 3Linked to original sources
PubMed1955

Studies on the endoplasmic reticulum. II. Simple dispositions in cells in situ.

A survey of a large number of different cell types has indicated the presence of a network of membrane-bound cavities (the endoplasmic reticulum) in the cytoplasm of all cell types examined, with the exception of the mature erythrocyte. In its simplest form, encountered in seminal epithelia and in leucocytes, the reticulum consists mainly of interconnected strings of vesicles and appears to be randomly disposed in three dimensions. Local differentiations occur within the endoplasmic reticulum of all the cell types studied. The membrane limiting the cavities of the endoplasmic reticulum appears to be continuous with the cell membrane and the nuclear membranes.

Animals↗
PubMed1955

A small particulate component of the cytoplasm.

A particulate component of small dimensions (100 to 150 A) and high density is described in the ground substance of the cytoplasm of mammalian and avian cells. In many cell types that seem to have in common a high degree of differentiation, the new component is preferentially associated with the membrane of the endoplasmic reticulum; whereas in other cell types, characterized by rapid proliferation, it occurs more or less freely distributed in the ground substance of the cytoplasm. In the Discussion an attempt is made to integrate the observations presented in this paper with the already available cytological, histochemical, and cytochemical information.

Animals↗
PubMed1955

The fine structure of neurons.

1. Thin sections of representative neurons from intramural, sympathetic and dorsal root ganglia, medulla oblongata, and cerebellar cortex were studied with the aid of the electron microscope. 2. The Nissl substance of these neurons consists of masses of endoplasmic reticulum showing various degrees of orientation; upon and between the cisternae, tubules, and vesicles of the reticulum lie clusters of punctate granules, 10 to 30 mmicro in diameter. 3. A second system of membranes can be distinguished from the endoplasmic reticulum of the Nissl bodies by shallower and more tightly packed cisternae and by absence of granules. Intermediate forms between the two membranous systems have been found. 4. The cytoplasm between Nissl bodies contains numerous mitochondria, rounded lipid inclusions, and fine filaments.

Animals↗
PubMed1954

Studies on the endoplasmic reticulum. I. Its identification in cells in situ.

A series of representative cell types including avian fibroblasts, and macrophages; rabbit mesothelia, endothelia, and nephron epithelia; and rat glandular epithelia (parotid) were studied comparatively in vitro and in situ with the electron microscope. Cells in vitro were examined in whole mounts and in sections whereas cells in situ were observed exclusively in sections. It was found that an endoplasmic reticulum similar to that previously described in cultured material is present in situ in all cell types examined. Modifications in its appearance introduced by the sectioning technique were discussed and explained. The observations showed in addition that the endoplasmic reticulum is a network of cavities which may enlarge into relatively vast, flattened vesicles here described as cisternae.

Animals↗
PubMed1952

A study of fixation for electron microscopy.

Osmium tetroxide fixation of tissue blocks, as usually effected, is preceded by an acidification of the tissue. This acidification is probably responsible for morphological alterations which are notably disturbing in electron microscopy. The acidification and the resulting morphological alterations cannot be prevented by homogenizing the tissue directly in OsO(4) solutions or by adding enzyme inhibitors (fluoride, iodoscetamide) to the fixative. Fixation experiments with buffered OsO(4) solutions have shown that the appearance of the fixed cells is conditioned by the pH of the fixative. The quality of fixation can be materially improved by buffering the OsO(4) solutions at pH 7.3-7.5, The acetate-veronal buffer appeared to be the most favorable of the buffers tested, Because of these findings, 1 per cent OsO(4) buffered at pH 7.3-7.5 with acetate-veronal buffer is recommended as an appropriate fixative for electron microscopy.

Electrons↗
PubMed1951

Intracellular localization of acid phosphatase; a comparative study of biochemical and histochemical methods.

The acid phosphatase activity of rat liver homogenates and of nuclear and cytoplasmic fractions isolated therefrom (by differential centrifugation) was determined biochemically in a series of experiments. For each liver, Gomori's histochemical test for acid phosphatase was run in parallel. No correlation was found between the biochemical and the histochemical results. According to the former, the enzyme appears to be almost entirely (95 per cent) located in the cytoplasm, while according to the latter, the acid phosphatase is predominantly concentrated in the nuclei and in some peribiliary polymorphic structures identified as myelin figures. It was found that the precipitaion pattern obtained in the histochemical test does not reveal, as generally assumed, differences in enzyme concentration among the various cell structures, but actually reveals differences in their lead phosphatase affinity. The usefulnes of the histochemical test for intracellular localization studies was found to be further limited by considerable fixation damage and formation of myelin figure artifacts. The biochemical approach is to be preferred because of better preservation of the material and direct and more reliable methods for the demonstraton of enzyme activity.

Acid Phosphatase↗