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E DE ROBERTIS

Publications and source records attributed to E DE ROBERTIS.

At least 19 recordsLinked to original sources
PubMed1963

Acetylcholine and cholinacetylase content of synaptic vesicles.

Acetylcholine, cholinacetylase, and acetylcholinesterase were determined in three subfractions that resulted from the osmotic shock of the "mitochondrial" fraction of the rat brain. Acetylcholine and cholinacetylase were found concentrated in the subfraction that contained mainly synaptic vesicles and some membranes, whereas the larger proportion of the acetylcholinesterase was observed in the subfraction that contained torn nerve endings. These results support the idea that synaptic vesicles are the morphological units of acetylcholine within the synapse.

Acetylcholine↗
PubMed1961

Plurivesicular secretory processes and nerve endings in the pineal gland of the rat.

The pineal body of white normal rats, 1.5 to 3 months old, was studied under the electron microscope. A single type of parenchymal cell-the pinealocyte-is recognized as the main component of the tissue, and some of the structural characteristics of the nucleus and cytoplasm are described. The main morphological characteristic of the pinealocytes is represented by club-shaped perivascular expansions connected to the cell by thin pedicles. They are found lying in a large, clear space surrounding the blood capillaries. The name plurivesicular secretory processes is proposed, to emphasize the main structural feature and the probable function of these cellular expansions. A tubulofibrillar component is mainly found in the pedicle, and within the expansion there are numerous small mitochondria and densily packed vesicles of about 425 A. Two types of vesicles, one with a homogeneous content and another with a very dense osmium deposit, are described. Between the two types there are intermediary forms. In these processes, mitochondria show profound changes which may lead to complete vacuolization. The significance of this plurivesicular secretory component is discussed in the light of recent work on the biogenic amines of the pineal body and preliminary experiments showing the release of the vesicles containing dense granules after treatment with reserpine. These vesicles are interpreted as the site of storage of some of the biogenic amines. Bundles of unmyelinated nerve fibers and endings on large blood vessels which also contain a plurivesicular content are described and tentatively interpreted as adrenergic nerve terminals.

Animals↗
PubMed1960

Electron microscopy of retinal photoreceptors. The use of chromation following formaldehyde fixation as a complementary technique to osmium tetroxide fixation.

The fine structure of the cone and rod outer segments of the toad was studied under the electron microscope after fixation in osmium tetroxide and fixation in formaldehyde followed by chromation. In the OsO(4)-fixed specimens, the rod outer segment appears to be built of a stack of lobulated flattened sacs, each of which is made of two membranes of about 40 A separated by an innerspace of about 30 A. The distance between the rod sacs is about 50 A. The sacs in the cone outer segment are originated by the folding of a continuous membrane. The thickness of the membranes and width of the spaces between the cone sacs is the same as in rod, but the sac innerspace is slightly narrower in the cone ( approximately 20 A). After fixation in formaldehyde and chromation, two different dense lines (l(1) and l(2)) separated by spaces of less density appear. One of the lines, l(1), has a thickness of 70 A and is less dense than the other, l(2), which is 30 A thick. The correlation of the patterns obtained with both fixatives is considered and two possible interpretations are given. The possibility that l(2) is related to a soluble phospholipid component is discussed. It is suggested that the outer segments have a paracrystallin organization similar to that found in myelin.

Animals↗
PubMed1960

Submicroscopic analysis of the genetic distrophy of visual cells in C3H mice.

The morphogenesis of the visual cells in the retina of DBA normal mice and in C3H mice having a genetic distrophy has been studied with the electron microscope. The stages of development previously described (3) have been confirmed. Two basal centrioles have been observed and an asymmetrical process of invagination of the surface membrane is recognized as the main source of the rod sacs in the outer segment. In the C3H mice the differentiation of the photoreceptors starts and reaches a certain stage but very early some alterations in the morphogenesis are observed. In the outer segment there appears a disorganized growth of membranous material that may invade the inner segment with disappearance of the normal connecting cilium. In the inner segment there is an increase of vesicular material and in the number of dense particles. In later stages the entire inner segment is filled with dense particles and the mitochondria degenerate. The synaptic junction with the bipolar cell, which reaches a certain degree of development, also shows early signs of degeneration. The observations reported have confirmed and extended the concept that the hereditary visual alterations of C3H mice are not the result of a primary arrested development but of a secondary alteration of the differentiating photoreceptor. In C3H mice the entire process of morphogenesis is disordered and leads to final involution and death. These findings are correlated with recent biochemical findings and are discussed with relation to the genetic mechanisms that may control normal morphogenesis.

Animals↗