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Biomedical subjects

M Jacob

Publications and source records attributed to M Jacob.

At least 271 records · Page 15Linked to original sources
PubMed1975

[The early differentiation of the perinotochordal connective tissue. A scanning and transmission electron microscopic study on chick embryos (author's transl)].

The early differentiation of the connective tissue was investigated in the perinotochordal zone of 2-3 day-old chick embryos. After characterizing the different tissue components by transmission electron microscopy, their arrangement and distribution were examined by SEM. The results are discussed with regard to the role of the extracellular material in embryonic tissue interactions.

Animals↗
PubMed1975

Salt dissociation of nuclear particles containing DNA-like RNA. Distribution of phosphorylated and nonphosphorylated species.

Electrophoresis of proteins from nuclear particles containing DNA-like RNA gave a pattern with 45 bands. The possibility that some of these proteins arose by contamination with ribosomes, chromatin, or soluble nuclear proteins was examined and eliminated. The fate of the proteins of the particles was studied after partial dissociation with 0.25 and 0.70 M NaCl. The individual proteins were released progressively and in different quantities. A group of easily released species (75 and 95% removed with 0.25 and 0.70 M NaCl) was demonstrated. This group contained 8 species between 29,000 and 39,000 daltons which represented approximately one-half of the total number of molecules. It is suggested that they are bound to repetitive sequences of the RNA. At least 30 and 60% of the other proteins were released at 0.25 and 0.70 M NaCl, respectively. There were no specific proteins tightly bound to the RNA, unless the nature of the remaining species is different from that of the released ones of the same molecular weight. The phosphorylated proteins were more tightly bound to the RNA than the nonphosphorylated species of similar molecular weight. In several instances, the 32-P radioactivity was associated with quantitatively minor bands of proteins.

Animals↗
PubMed1975

Neural intersegmental connection in the spinal root and ganglion region of the rat.

A study has been made of the macroscopic, microscopic and electron-microscopical appearance of intersegmental neural connections in the rat. Macroscopically, spinal roots and ganglia of adjacent segments were frequently observed to be linked by discrete, slender strands, mainly in the lumbosacral region where the roots are long. When examined under the light microscope, even the smallest was found to contain as many as 72 myelinated fibres with a range of diameters between 1.5-14 mu-m. The were commonly accompanied by blood vessels. Connections, when present, contributed to as much as 6-28% of the total number of myelinated axons in dorsal roots. Under the electron microscope, links between dorsal roots, or between dorsal roots and adjacent ganglia, contained unmyelinated fibres comparable in numbers to those found in the dorsal roots themselves. In links between ventral roots and ganglia the numbers of unmyelinated fibres proportionally exceeded those found in ventral roots. The presence of these connections may account for the reported finding of undamaged nerve fibres in the dorsal roots after dorsal root sectioning or ganglionectomy and in the ventral roots after ventral root sectioning.

Animals↗