PubMed Health⌕ Search

Biomedical subjects

J Trubatch

Publications and source records attributed to J Trubatch.

11 recordsLinked to original sources
PubMed1979

Progression of fusion during rapid freezing for electron microscopy.

The method used to determine the rate of fusion was based on the large difference in the dielectric constants of water and ice. A thin (50--60 micrometers) slice of a gelatin gel was used as the dielectric in a plate condenser. The slice was placed on a metal electrode built in a specimen carrier which was dropped on a silver freezing surface kept at below 70 K, forming the other plate of the condenser. Freezing of the gelatin causes a marked decrease in a 20,000 cycle current passing through the condenser. Since the thickness of the layer of frozen material was shown to be a function of the reciprocal of the current, it was possible to determine the course of fusion of the section. Freezing started at a high rate which declined during the first 5 ms but then increased again and usually became quite high at the end of fusion.

Animals↗
PubMed1975

Synaptic changes in frog brain after stimulation with potassium chloride.

In vitro preparations of frog brains, stimulated by application of CKl were fixed by freeze substitution and examined electron microscopically. Control preparations were bathed in a calcium-free physiological solution with Mg added or in salt solution cooled to 5-10-degrees C. The isolated brain remains viable in the physiological solution as indicated by the direct cortical responses which can be led off from the forebrain. Control preparations were characterized by a row of vesicles situated close to the presynaptic membrane and by the absence of a well-developed postsynaptic web. In KCl stimulated preparations there were, in addition to synapses resembling those in the controls, synapses exhibiting fusion of synaptic vesicles with the membrane of the axonal ending, synapses in which the vesicles had retreated from the presynaptic membrane but were attached to it by a narrow stalk and synapses exhibiting a pronounced postsynaptic web. The synaptic gap was of a less uniform width than in the control preparations. The KCl stimulated preparations were furthermore characterized by a paucity of extracellular space and often showed invaginations formed by the presynaptic membrane and the plasma membranes of the postsynaptic or adjacent glial structure.

Animals↗