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  • Morphogenesis  (1)
  • Pineal body  (1)
  • 1970-1974  (2)
  • 1
    ISSN: 1432-0568
    Keywords: Lysosome ; Autophagy ; Phagocytosis ; Acid phosphatase ; Morphogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The ultrastructure of the “physiological” cell death was studied in distal ventral bulbar cushions of 15 chick embryo hearts on the 4th and 5th day of incubation. Microperfusion fixation was performed. The ultracytochemistry of a lysosomal hydrolytic enzyme acid phosphatase was also investigated in another 15 embryonic hearts. In the course of the cell degeneration an increase in cellulr autophagy was observed without previous cytoplasmic or nuclear changes or phagocyte ingestion. A cytoplasmic diffusion of acid phosphatase outside of lysosomes was observed. Besides the cell death with the marked participation of the lysosomal system, another kind of dying cells was found, characterized by their nuclear pycnosis and cytoplasmic condensation. Starting from the 5th day of incubation the dying and dead cells were found phagocytized by some of their neighbouring viable mesenchymal cells. A formation of ribosomal crystals was not observed. The formation and fate of cytolysomes as well as the fate of phagocytes are discussed. The presence of pre-necrotic cells with important autophagy and of necrotic cells with nuclear changes was related to the possibility of a dual cause of the cell death. In the case of pre-necrotic cells the epigenetic factors like the biomechanic action of hemodynamics were considered, while the necrotic cells seem to be programmed to death by their genome. Finally the uniformity of cell death ultrastructure in different organs and species was noticed.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0878
    Keywords: Pineal body ; Wistar rat ; Striated muscle fibers ; Triads ; Helicoidal polyribosomes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Unter 35 Pinealdrüsen von erwachsenen Wistar-Ratten wurden 8 mit quergestreiften Muskelfasern gefunden. Diese liegen in der Peripherie des Organs und in der Nähe des Pinealstiels. In 3 Fällen wurden direkte Kontakte zwischen Muskelfasern und Kapillaren gesehen. Die Pinealmuskelfasern besitzen ein Sarkolemma, das aus einer Basalmembran und einem retikulären Fibrillengitter aufgebaut ist. Mehrere Merkmale, die für embryonale Muskelfasern charakteristisch sind, werden in den Pinealmuskelfasern gefunden: Reichtum am Sarkoplasma, Armut an Myofibrillen, helikoidale Polyribosomen, unterschiedlich lokalisierte und häufig longitudinale Triaden, Übergang von granulärem in agranuläres sarkoplasmatisches Retikulum, Anzeichen mikropinozytotischer Prozesse, ungeordnete Myofilamente und primitiv gebaute A-Bänder. Die A- und I-Bänder sind in Längsschnitten gut sichtbar, während H-Zonen und M-Streifen meistens fehlen. Die Z-Streifen, gut ausgebildet nach jeder Fixation, sind nie reglemäßig und geradlinig wie in der Skelettmuskulatur. Die Länge einer Sarkomere beträgt 1,25–1,4 μm nach OsO4-Fixation und 2,4–3,1 μm nach Aldehydvorfixation. Soweit elektronenmikroskopische Befunde ein Urteil erlauben, dürften die Pinealmuskelfasern — obwohl embryonalen Charakters — kontraktionsfähig sein. In einem Fall wurde ein wahrscheinlich (neuro)endokrino-muskulärer Kontakt zwischen einer Muskelfaser und einem Pinealzellausläufer gefunden.
    Notes: Summary 8 of 35 pineal bodies obtained from adult male Wistar rats were found to contain striated muscle fibers. These are located at the periphery of the pineal body or in close proximity to the pineal stalk. In 3 cases a direct contact between capillaries and muscle fibers was observed. The pineal muscle fibers possess a sarcolemma which is formed by the basal membrane and a network of reticular fibers. Several features characteristic of embryonic muscle fibers are found in the fibers of the pineal body: abundance of sarcoplasm, scarce myofibrils, helicoidal polyribosomes, triads variously located and frequently longitudinally oriented, transition of rough- to smooth-surfaced endoplasmic reticulum, presence of micropinocytotic vesicles and primitively formed A-bands. A- and I-bands are well visible in longitudinal sections, while H- and M-bands are mostly lacking. The Z-lines, well formed after every fixation, are never regular and straight as seen in skeletal muscles. After fixation in OsO4 the length of a sarcomere is 1,25–1,4 μm, after aldehyde prefixation it is 2,4–3,1 μm. According to electron microscopic findings the pineal muscle fibers, although being of embryonic character, seem to have the ability to contract. In one case a possibly (neuro)endocrino-muscular contact between a muscle fiber and a pineal cell process has been observed.
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