Electron microscopic and autoradiographic study of the pancreas at different times of postmortem ischemia]

Experiments on dogs showed that the maximally admissible term of normothermic postmortem ischemia of the pancreas should not exceed 45 minutes, because irreversible destructive changes in the ultrastructural formations of the exocrine parenchyma cells developed later. The Langerhans islet cells proved to be more resistant to the ischemic effect.     

Electron microscopic study of troponin

Troponin and its components or fragments were observed in an electron microscope by the use of the rotary shadowing technique. In freshly prepared troponin with low viscosity, globular particles were mainly observed. The size of the long axis of the particles was 13.2 +/- 1.3 nm and the size perpendicular to the long axis was 9.5 +/- 1.2 nm. The mean axial ratio was 1.4 +/- 0.3. Most of the particles observed in a stored troponin preparation, having a higher viscosity than that of fresh troponin, had a globular head with a thin tail, with the total length of 25.4 +/- 1.4 nm (head-tail type particles). The axial size of the globular portion was 8.3 +/- 1.2 nm and the tail length was 17.1 +/- 1.6 nm. Observation of various particles during the transitional stages indicated that, in the globular particles, the tail region of head-tail type particle was associated along the globular head region. Troponin T was a filamentous particle with 16.9 +/- 1.5 nm length. The 26K fragment of troponin T, which was devoid of the N-terminal 45 residues from troponin T, was a filamentous particle with the length of 14.4 +/- 1.3 nm. Troponin T1, one of two chymotryptic subfragments of troponin T, was a filamentous particle of 11.6 +/- 1.4 nm length. Troponin C.T in the presence of Ca2+ was a particle with a globular head (7 nm in size) and a tail of about 17 nm length. The Fab fragment of anti-troponin T1 formed regular transverse striations along the thin filament of rabbit skeletal muscle with a 38 nm period.(ABSTRACT TRUNCATED AT 250 WORDS)     

Electron microscopic study of the epiphysis in the hen in different age periods

Electron microscopic investigation of the epiphysis in 1 and 2 years old hens revealed that pineocytes are rich in mitochondria, ribosomes, granular endoplasmic network, Golgi apparatus, synapses. In contrast to 1-year hens, large amounts of lipofuscin granules and lysosomes were found in older animals. The data obtained reveal intensive hormone formation and oxidation-reduction processes in the epiphysis of birds.     

Electron microscopic study of alpha-actinin.

Electron microscopic studies of the structure of purified α-actinin alone and in complex with F-actin have determined the molecular shape and size of this protein. α-Actinin molecules represent rods of about 300 Å in length and about 20 Å in diameter.     

Electron microscopic study of forest soil

Scanning electron microscopy was used to evidence the aggregated structure of a forest soil as well as the presence of fungal hyphae external to soil aggregates. The supernatant of soil suspension in water mainly contained isolated bacteria, while ultrathin sections of aggregates frequently revealed groups of bacteria surrounded by a sheath of mucilage with adhering clay minerals on the outside. These results confirm the existence of two particular biotopes in the soil studied: one is located inside aggregates, and the other, in the inter-aggregate spaces.     

Electron microscopic study of meningococci in stab cultures

The study of the ultrastructure of meningococci (strain C0638) in the process of submerged batch cultivation permitted the authors to follow changes in the fine structure of these microorganisms in different phases of the growth of the culture. Thus, the meningococcal populations retained their ultrastructure most intact during the exponential phase and the growth rate deceleration phase. During these growth phases a faintly pronounced reaction of the surface structures with ruthenium red was observed. In the stationary phase and in the atrophy phase this reaction was completely absent. The accumulation of exotoxin bubbles in the membrane was shown to achieve its maximum in the atrophy phase; besides, these structures regularly appeared at the death of the cells under the action of alkali. A hypothesis explaining the appearance of these bubbles is put forward.