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V Sundararaman

Publications and source records attributed to V Sundararaman.

13 recordsLinked to original sources
PubMed1979

The ultrastructure of the striated muscle of the tail of Cercaria chackai, nadakal et al., 1969.

The electron microscopic study of the tail of Cercaria chackai reveals that it contains four sets of striated muscle bundles located central to the nonstriated circular and longitudinal muscles. The striated muscle consists of longitudinally oriented lamellar myofibres. Each myofibre contains a single "U" shaped myofibril. The banding pattern is analogous to that of vertebrate striated muscle. The sarcolemma is a simple surface membrane. There are no transverse tubular extensions of sarcolemma. The sarcoplasmic reticulum (SR) is very well developed with cisternae, tubules, and vesicles. SR cisternae form dyadic couplings with the sarcolemma. There is a set of flattened tubules of SR origin traversing the myofibril exactly at the Z region. These tubules are unique to the striated muscle of the cercarian tail and may have functional significance. A diagrammatic reconstruction of the myofibre is presented.

Animals↗
PubMed1975

Dose distributions and mean doses in cylindrical cavities of bone marrow on X-ray irradiation.

Dose distributions as well as mean doses to cylindrical cavities of bone marrow on X-ray irradiation have been calculated using (a) Monte Carlo method and (b) a simplified straight line approximation method. The results are compared with earlier published ones. Point doses differ appreciably from the earlier results by as much as 40 percent at some points, whereas mean doses agree to within 10 percent for all the three methods.

Bone Marrow↗
PubMedDate not supplied

Morphological changes in aging cell lines of Paramecium aurella. I. Alterations in the cytoplasm.

Electron microscopical examination of aging P. aurelia revealed that definitive changes occur in the cytoplasm of old cells. There was an increase in the number of mitochondria and lysosomal bodies as well as the appearance of large dense bodies and autophagous vacuoles. The mitochondria were altered morphologically and many appeared to be coalesced with lysosome-like bodies and were also observed to be degenerating within autophagous vacuoles. The large dense bodies were considered to be similar to the lipofuscin or age pigments reported in other aging cells. The relationship of the large dense bodies to the lipofuscin pigments and their probable origin are discussed as is the involvement of the cytoplasm in the aging death process in P. aurelia.

Aging↗
PubMedDate not supplied

Morphological changes in aging cell lines of Paramecium aurelia. II. Macronuclear alterations.

Electron microscopic examination of aging P. aurelia showed that the macronucleus undergoes characteristic structural changes. The surface of the aging macronucleus was highly invaginated. Compared with young macronuclei, the chromatin bodies appeared to be smaller and condensed, and were fewer per unit area of the aging macronucleus. The nucleolar bodies also showed morphological alterations. In many aging macronuclei the nucleolar bodies appeared to be aggregated. Large ring-shaped or coiled loops of nucleoli were also observed. These changes in the ultrastructure of macronucleus in the aging paramecia suggest that the macronucleus in the aging cells is less active in the synthesis of macromolecules and transport of material to the cytoplasm.

Animals↗
PubMedDate not supplied

Morphological changes in aging cell lines of Paramecium aurelia. III. The effects of emetine on polysome formation.

The effect of emetine, an inhibitor of cellular protein synthesis, on young and old cell lines of Paramecium aurelia was studied. Emetine treatment resulted in the accumulation of ribosomal aggregates in the form of helices or rosettes. In treated young cells, large patches of endoplasmic reticulum with clusters of ribosomes were frequently observed. These structures were smaller in treated aging cells. Owing to the association of these ribosomal clusters with endoplasmic structures, they were called "ribosomal complexes". In young cells the polysome helices were more numerous, compared to those of old cells. The difference in the number of polysomes between the young and old cells appeared to be related to the number of ribosomes. The results suggested that in aging cells there were fewer ribosomes and less RNA. In very old cells the ribosomal particles appeared to be altered morphologically.

Animals↗