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Biomedical subjects

J D ROBERTSON

Publications and source records attributed to J D ROBERTSON.

At least 37 records · Page 2Linked to original sources
PubMed1956

The ultrastructure of a reptilian myoneural junction.

Myoneural junctions in Anolis are characterized by the formation of troughs in the surface of the muscle fibers in which small branches of the terminal axon lie. The muscle surface membrane lining the troughs is thrown into complex branching and anastomosing folds, which compose the subneural apparatus of Couteaux. A compound membrane 500 to 700 A thick separates axoplasm from sarcoplasm at the endings. This consists of five distinct layers and is described in detail. A thin layer of cytoplasm (probably Schwann) separates terminal axoplasm from extracellular space at the surfaces of the junctional troughs. Terminal axoplasm lacks axoplasmic filaments and contains numerous vesicular or tubular appearing structures about 300 to 500 A in diameter. Both terminal axoplasm and sarcoplasm contain numerous mitochondria.

Axons↗
PubMed1955

The ultrastructure of adult vertebrate peripheral myelinated nerve fibers in relation to myelinogenesis.

Adult chameleon myelinated peripheral nerve fibers have been studied with the electron microscope in thin sections. The outer lamella of the myelin sheath has been found to be connected as a double membrane to the surface of the Schwann cell. The inner lamella is connected as a similar double membrane with the double axon-Schwann membrane. The relations of these double connecting membranes suggest that the layered myelin structure is composed of a double membrane which is closely wound about the axon as a helix. These findings support the new theory of myelinogenesis proposed recently by Geren. The possible significance of these results with respect to cell surface membranes and cytoplasmic double membranes is discussed.

Animals↗