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R C BUCK

Publications and source records attributed to R C BUCK.

At least 19 recordsLinked to original sources
PubMed1965

STRUCTURE OF THE MITOTIC SPINDLE IN L STRAIN FIBROBLASTS.

The mitotic spindle of L strain fibroblasts, fixed with glutaraldehyde followed by osmium tetroxide, contains many 150- to 180-A tubules. They appear first in the cytoplasm. They extend from the centrospheres to the kinetochores, and from one centrosphere to the other. Only occasionally can points of continuity between the spindle tubules and the tubules of the centrioles be observed. The chromosomal insertion is by a means of a thin dense plate of the kinetochore. The total number of continuous spindle tubules is between 500 and 600. Occasionally, tubules appear paired. At anaphase, short lengths of individual spindle tubules possess a coating of a substance of high density midway between the poles. These parts of the spindle tubules aggregate to form irregular groups, comprising the stem-body, and, by becoming aligned into a plate, they form the mid-body.

Anaphase↗
PubMed1962

The fine structure of the mid-body of the rat erythroblast.

The development of the mid-body has been studied in mitotic erythroblasts of the rat bone marrow by means of thin sections examined with the electron microscope. A differentiated region on the continuous spindle fibers, consisting of a localized increase in density, is observed at the equatorial plane. The mid-body seems to develop by the aggregation of such denser lengths of spindle fiber. Its appearance precedes that of the cleavage furrow. A plate-like arrangement of fibrillary material lies transversely across the telophase intercellular bridge. Later, this material becomes amorphous and assumes the form of a dense ring closely applied to a ridge in the plasma membrane encircling the middle of the bridge. Although the mid-body forms in association with the spindle fibers, it is a structurally distinct part, and the changes which it undergoes are not shared by the rest of the bundle of continuous fibers.

Animals↗
PubMed1962

An electron microscopic study of the cleavage furrow in mammalian cells.

The process of cytoplasmic cleavage has been studied in thin sections of rat erythroblasts and the cells of mouse leukemia and Walker 256 carcinoma of the rat. The development of the cleavage furrow begins in relation to the mid-body, which, earlier, appears on the equatorial plane in association with the continuous fibers of the spindle. The earliest evidence of a cleavage furrow is the presence of a vesicle or vesicles close to the mid-body. Subsequently, many smaller vesicles are seen in the equatorial plane. The cleavage furrow probably develops by the fusion of these vesicles so that a new plasma membrane is formed between the daughter cells, and extends from the telophase intercellular bridge to the cell margin. During the stage of formation of the vesicles, cisternae, believed to be part of the endoplasmic reticulum, assume an intimate relationship with the cleavage plane, and they may perhaps be involved in the formation of the vesicles.

Animals↗
PubMed1961

Lamellae in the spindle of mitotic cells of Walker 256 carcinoma.

In mitotic cells of Walker 256 carcinoma some four-layered lamellar structures were observed which had the appearance of paired cysternae of the ER. Two inner membranes were regular, smooth surfaced, and closely applied to each other. The two outer membranes were somewhat irregularly placed in relation to the inner pair; they showed attached RNP particles and connections with cysternae of the ER. The membranes often appeared to radiate from the region of the centrosphere towards the compact mass of chromosomes. Thus, they lay amid the spindle fibres and are referred to as "spindle lamellae." They approached the centrioles closely but were not observed to be continuous with them. They appeared to terminate in the pole of the spindle by joining smooth surfaced membranes in the centrosphere. Their equatorial termination was in relation to the chromosomes. At the surface of the chromosome mass they frequently split into two double membranes, which were closely applied to the chromosome substance. The most prominent and complicated membranes were seen in anaphase cells. An hypothesis is advanced which ascribes the development of the nuclear membrane to the spindle lamellae.

Anaphase↗
PubMed1958

The fine structure of endothelium of large arteries.

Endothelium of large arteries from several species was studied in thin sections with the electron microscope. Before sacrifice, some animals received an intravenous injection of colloidal thorium dioxide which was visualized in the sections. Surface replicas were prepared by carbon evaporation on either frozen-dried endothelium or on endothelium dried by sublimation of naphthalene with which the tissue had been impregnated. Cell boundaries, stained with silver, were observed in sections and also from the surface by stripping off the inner part of the endothelium. In addition to the usual cytoplasmic organelles, the endothelial cells showed certain characteristic features, namely, large invaginated pockets communicating with the arterial lumen, numerous much smaller vesicular structures immediately under the plasma membrane and apparently also communicating with the lumen, and inclusions, into which injected thorium particles were incorporated. Intercellular boundaries appeared as regular double membranes in thin sections, and they were outlined by a double row of silver granules after silver staining. No evidence was obtained of permeation of intracellular spaces by colloidal thorium.

Animals↗