PubMed Health⌕ Search

Biomedical subjects

C Stolinski

Publications and source records attributed to C Stolinski.

32 records · Page 2Linked to original sources
PubMed1979

Membrane specializations and cytoplasmic channels of Schwann cells in mammalian peripheral nerve as seen in freeze-fracture replicas.

Mammalian Schwann cells in rat, rabbit and human fetal nerves were studied using several cryoprotective agents for electron microscopic study of freeze-fracture replicas. The findings in fixed and unfixed tissue reveal surface plasmalemma caveolar specializations and the outer layer membrane junctional complexes found in non-mammalian species. The plasmalemma also reveals a complex arrangement of contours outlining cytoplasmic channel networks distinct from the long-recognized Schmidt-Lanterman incisures and paranodal cytoplasmic loops. A specialized interconnected channel system in the outer "loose" myelin layer displays relatively uniform dimensions comparable in diameter to nodal microvilli, paranodal loops and some incisures. An adaxonal tubular channel system constituting the "axon-Schwann network" is found in the internodal region in addition to other variants of the adaxonal Schwann plasmalemma. The several forms of sequestration of Schwann cell cytoplasm presumably underlie the specialized needs of cytoplasmic continuity in a dynamic functional entity in which large domains of cytoplasm have been displaced by the formation of compact myelin.

Animals↗
PubMed1978

Effect of fixation on cell membrane of early embryonic material as observed on freeze-fracture replicas.

Some cell membranes of chemically fixed, cryoprotected and freeze-fractured chick embryonic material are characterized by 150-250 nm diameter circular smooth blebs. No such blebs are observed, however, on cryoprotected, rapidly frozen but not chemically fixed samples. It is concluded, therefore, that fixation with buffered glutaraldehyde and not cryoprotection with glycerol is mainly responsible for the appearance of the blebs. The suggestion that blebs represent a budding virus is not tenable, since blebs are present in material obtained from virus free embryos.

Animals↗
PubMed1977

Freeze-fracture replication and surface sublimation of frozen collagen fibrils.

Collagen fibrils from various rapidly frozen mammalian tissues were examined by the technique of straightforward freeze-fracture, freeze-fracture followed by sublimation and surface sublimation technique. Fixed and non-fixed specimens cryoprotected either with glycerol or dimethylsulphoxide (DMSO), as well as non-cryoprotected ones, were examined. Fibrils were observed either with a banded pattern or as helically twisted strands, and in some cases as a combination of both arrangements. Minimally processed fibrils presented a clearcut banded appearance, while the helical pattern seemed to be associated with the presence of the cryoprotectant, glycerol and DMSO. It is concluded that the banded appearance is in all probability a normal feature of the collagen fibrils in vivo, and that the helical pattern is an abnormal feature resulting from various pretreatments of tissue.

Animals↗
PubMed1976

Direct observation of immunoglobulins on the erythrocyte membrane.

A modification of the sublimation procedure for observation of cell membrane exteriors is described. By retaining basic advantages of the freeze-fracture technique, without actual fracturing of the sample, high quality replicas can be produced on which molecules such as immunoglobulins can be identified and mapped on extensive areas of the erythrocyte membrane surfaces. The method can be used for direct observation of antibodies without recourse to labelling with other marker molecules, such as for example ferritin. In addition, direct visualization of clumping of red cells, as induced by such antibodies, is feasible.

Cell Membrane↗
PubMed1976

A comparison of membrane fracture faces of fixed and unfixed glycerinated tissue.

Fixed (glutaraldehyde, 3%) and unfixed specimens of rat buccal epithelium, striated muscle, and liver, were cryoprotected with glycerol, freeze-fractured, and replicated without sublimation. A comparison of fracture faces of general plasma membranes, nuclear membranes, mitochondrial membranes, and membranes of rough endoplasmic reticulum revealed no significant differences as between fixed and unfixed material. Apart from some membranes of liver endoplasmic reticulum, there was no evidence of aggregation or redistribution of intramembranous particles in the unfixed material. The results demonstrate that chemical prefixation of tissues for freeze-fracture is not always necessary, or even desirable, and that glycerol may not be as deeply or directly implicated in particle aggregation as previously thought. Fixation with glutaraldehyde alters the cleaving behaviour of plasma membrane at desmosomes and tight junctions, but not at gap junctions.

Animals↗
PubMed1976

Freeze-fracture replication of organized tissue without cryoprotection.

Fresh pieces of rat liver and pancreas were rapidly frozen without prior chemical fixation or cryoprotection, and replicated folloing freeze-fracture. Replicas revealed small peripheral areas free of ice crystals or damage and, within such areas, general ultrastructural morphology was essentially similar to that seen in conventionally processed material. On fracture faces of plasma and nuclear membranes a population of less prominent particles in addition to conventional membrane-associated particles was seen, and smooth areas devoid of particles of any type were seen on some nuclear membranes. These smooth areas did not appear to be similar to smooth areas allegedly arising as artifacts of conventional processing. Tight junctions and gap junctions appeared as they do in cryoprotected specimens. The results provide a base-line for assessing the possible effects of processing steps or agents on the ultrastructure of organized tissues as revealed in freeze-fracture replicas.

Animals↗
PubMed1975

Distribution and mobility of the A, D and c antigens on human red cell membranes: studies with a gold-labelled antiglobulin reagent.

Studies are presented in which a gold-labelled anti-IgG reagent has been used to map the distribution of A, D and c antigen sites on the human red cell membrane. Red cells were combined with IgG antibodies; ghosts were produced which were then labelled with gold-anti-IgG. D antigen sites were found to be single entities dispersed on the red cell membrane of lysed but otherwise untreated Rh positive cells. Following papain treatment prior to lysis, a clustered distribution was observed. Clustering of D sites was also observed on non-enzyme-treated red cells of the -D- phenotype. Further studies indicated that D and c antigen sites are closely associated on ccDEE red cells. The distribution of A antigen sites was found to be clustered in proportion to the amount of IgG anti-A combined with the cells. Reasons are given for considering such distribution as indirect evidence of mobility of A sites. There was an association between agglutinability of red cells by IgG antibodies and the extent of the clustering of the antigen sites.

ABO Blood-Group System↗
PubMed1975

A freeze-fracture replication apparatus for biological specimens.

A freeze-fracture apparatus of original design has been constructed which can be fitted onto a standard vacuum evaporator unit. In it, cell suspensions and organized tissue may be processed by inserting a sample into a cylindrical holder. By leaving a small part of the tissue protruding from the holder, pre-selected and aligned portions of the specimen can subsequently be revealed by fracture under vacuum. After rapid freezing, the specimen remains firmly attached to the inner wall of the sample holder, preventing its possible loss during fracturing. A mechanism, in the form of a double-sided converging wedge, which is operated from outside the vacuum chamber, is used to produce a fracture in the specimen. The device gently induces a fracture in the desired part of the tissue and lifts the protruding part of the specimen out of the way. In this way, reasonably flat fracture faces are produced for subsequent replication. As the fracturing mechanism comes into contact only with the outer edges of the specimen, damage and contamination liable to occur when the entire specimen is traversed by a blade, is avoided. In addition the specimen stage is surrounded by a cold metal shroud which acts as an efficient trap for contaminants. In this way, favourable vacuum conditions are produced in the vicinity of the specimen. Such effective enclosing of the specimen also facilitates controlled sublimation of the sample.

Freeze Fracturing↗