Comparative evaluation of morphofunctional organization of vertebrate nuclear blood cells

Morphometrical parameters, osmoregulatory possibilities, and the membrane reserve value of nuclear hemocytes (leukocytes and erythrocytes) were studied in the main classes of vertebrates by using method of hypoosmotic loads. It has been established that in the fish--mammals line in erythrocytes the absolute reserve of the plasmalemma decreases and the relative area of the cell surface increases. Evolution of leukocytes is accompanied by an increase of the membrane reserve and of the surface area due to a decrease of volume and to a rise of folding of the plasmalemma.     

Comparative evaluation of morphofunctional organization of nucleated blood cells of vertebrate animals

Morphometrical parameters, osmoregulatory possibilities, and the value of membrane reserve of nucleated hemocytes (leukocytes and erythrocytes) of the main vertebrate animal classes were studied with use of the method of hypoosmotic loadings. It has been established that in erythrocytes, in the fish??mammal row, the absolute reserve of plasmalemma increases, while the relative area of the cell surface decreases. Evolution of leukocytes is accompanied by an increase of the membrane reserve and the surface area at the expense of a decrease of the volume and a rise of folding of the plasmalemma.     

Variation of ultrastructural organization of the mitochondria of pea cells in vitro

Unusual huge organelles together with mitochondria of typical organization were found in a part of population of callus cells of pea. They like mitochondria are surrounded by two biologic membranes, the inner one has invaginations. Inclusions in the matrix are a specific character of structural organization of these unusual mitochondria. These inclusions look as electronically dense bars that extend parallel to longitudinal axis of organelle and consist of fibril-like elements. Organization of inclusions and cristae as well as a shape of organelles are changing during cell development. Possible nature of the unusual mitochondria is discussed.     

Influence low-intensity laser irradiation on the ultrastructural organization of loach embryo cells

The ultrastructural organization of loach embryo cells (Misgurnus fossilis L.) at the stage of the first and the tenth embryo divisions was investigated under the influence of low intensity helium-neon laser irradiation of 5 min exposure. It was determined that the effect of laser irradiation led to ultrastructural changes: the shape of mitochondria and multivesicular bodies changes. The obtained results explain the possible mechanism of influence of low-intensity laser irradiation at the cellular level.     

The ultrastructural organization of gap junctions between follicle cells and the oocyte in Xenopus laevis

The cellular contact sites between the full-grown oocyte of Xenopus laevis and the surface extensions of surrounding follicles cells were analysed by electron microscopy of ultrathin sections, freeze-fracture replicas and critical point-dried specimens. Evidence is given for the presence of clusters of intramembranous particles (IMPs) at the P-face which represent gap junctions in diverse forms. Most common are maculae (phi 0.2-0.5 micron) of densely packed IMPs (phi 12 +/- 2 nm) which represent focal gap junctions generally found at the tips of follicle cell surface extensions. Inside many maculae an IMP-free area occurs which appears as a smooth disk (phi 70-80 nm) at both fracture faces. Occasionally a few IMPs are trapped within the smooth disks. Beside the maculae, networks of arrayed IMPs occur that enclose several smooth disks. These latter gap junctions probably are more frequent in side-to-side contacts between surface extensions of the oocyte and the follicle cells. The possible function of these IMP networks is discussed as being related to similar membrane specializations in excitable cells. In addition, indirect evidence was found that the extensions of the follicle cells transport yolky material.     

Effect of single-stranded breaks on the ultrastructural organization and cytochemistry of the chromatin in tumor cells

Single-stranded DNA breaks in Zajdela's ascitic hepatoma and transformed hamster fibroblasts were caused by treating alive cells with 1% dimethylsulfoxide for 2 h or 100 micrograms/ml bleomycin for 5 min and tested by alkaline and neutral DNA elutions. Electron microscopy of thin sections revealed decompaction of the loosened approximately 25 nm globules within diffuse chromatin into thin fibrillar mesh while supranucleosomal structure of the compact chromatin remained untouched. The chromatin enhanced its affinity for cationic dyes and contrast agents. It is concluded that the diffuse chromatin possesses torsional stress of DNA superhelicity and its loosened subunits represent a form for its organization. They probably correspond to the functionally active (dynamic) nucleosomes which display destruction under DNA domain relaxation caused by one-strand breaks.     

Macromolecular and ultrastructural organization of the mitotic chromosome scaffold

Using electron microscopy (EM), we have examined three structural domains of the mitotic chromosome scaffold of mouse erythroleukemia (MEL) Friend cells with different morphologic organization: centromeric, intermediate, and telomeric. The intermediate, most extensive, domain exhibited a specific fibrogranular structure representing tightly packed granular bodies with diameters between 20 and 60 nm. The chromosome scaffold contained three main components: proteins (81%), RNA (12%), and DNA (7%). The residual DNA extracted from the scaffold represented short fragments, 300 bp on average, belonging to the class of tandemly arranged repetitive DNA. In situ hybridization experiments confirmed its typical centromeric location. Scaffold RNA represented three fractions: a major RNA fraction with an electrophoretic mobility corresponding to that of 5S RNA and two minor fractions with electrophoretic mobilities somewhat lower than that of 18S RNA. Scaffold RNA was localized mainly in the centromeric region. We show that the newly synthesized protein component of the chromosome scaffolds migrates slowly to the chromosomes, reaching a maximum specific radioactivity 12 h from the onset of the chase period.     

The neuroanatomical and ultrastructural organization of statocyst hair cells in the pond snail, Lymnaea stagnalis

The ultrastructure, neuroanatomy and central projection patterns, including the intercellular connections of the statocyst hair cells of the pond snail, Lymnaea stagnalis, were studied, applying different intra- and extracellular cellular staining techniques combined with correlative light- and electron microscopy. Based on the ultrastructure different hair cells could be distinguished according to their vesicle and granule content, meanwhile the general organization of the sensory neurons was rather uniform, showing clearly separated perinuclear and "vesicular" cytoplasmic regions. Following intra- and extracellular labeling with fluorescence dyes or HRP a typical, local arborization of the hair cells was demonstrated in the cerebral ganglion neuropil, indicating a limited input-output system connected to the process of gravireception. Correlative light- and electron microscopy of HRP-labeled hair cells revealed both axo-somatic and axo-axonic output contacts of hair cell varicosities, and input on sensory axons located far from the terminal arborizations. Our findings suggest (i) a versatile ultrastructural background of hair cells corresponding possibly to processing different gravireceptive information, and (ii) the synaptic (or non-synaptic) influence of gravireception at different anatomical (terminal, axonal and cell body) levels when processed centrally. The results may also serve as a functional morphological background for previously obtained physiological and behavioral observations.     

The organization of the sarcoplasmic reticulum in teleost ventricular myocardial cells

Summary The morphology of the sarcoplasmic reticulum in myocardial cells of the ventricle of the trout heart is described as the result of an investigation with the electron microscope. The sarcoplasmic reticulum is sparse in distribution compared to that of birds or mammals but shows a fundamentally similar organization. A very loose network of fine tubules is in intimate contact with the myofibrils but with no local modification with respect to the arrangement of myofilaments within the sarcomeres. There is no special association of the sarcoplasmic reticulum with the Z-bands. Some tubules pass to the cell periphery where they expand to form subsarcolemmal cisternae in which electron-dense matter is often seen. The occurrence of the subsarcolemmal cisternae (peripheral couplings) is random and they are not observed in the vicinity of intercalated discs. The sarcoplasmic reticulum is discussed in relation to excitation-contraction coupling in teleost myocardial cells, and in comparison with that of other vertebrates.I am grateful to Professor J. D. Lever for making certain facilities available, and to Mr. P. F. Hire for photographic assistance.     

Immunohistochemical and ultrastructural localisation of peptide-containing nerves and myocardial cells in the human atrial appendage

Summary The innervation and myocardial cells of the human atrial appendage were investigated by means of immunocytochemical and ultrastructural techniques using both tissue sections and whole mount preparations. A dense innervation of the myocardium, blood vessels and endocardium was revealed with antisera to general neuronal (protein gene product 9.5 and synaptophysin) and Schwann cell markers (S-100). The majority of nerve fibres possessed neuropeptide Y immunoreactivity and were found associated with myocardial cells, around small arteries and arterioles at the adventitial-medial border and forming a plexus in the endocardium. Subpopulations of nerve fibres displayed immunoreactivity for vasoactive intestinal polypeptide, somatostatin, substance P and calcitonin gene-related peptide. In whole-mount preparations of endocardium, substance P and calcitonin gene-related peptide immunoreactivities were found to coexist in the same varicose nerve terminals. Ultrastructural studies revealed the presence of numerous varicose terminals associated with myocardial, vascular smooth muscle and endothelial cells. Neuropeptide Y immunoreactivity was localised to large electron-dense secretory vesicles in nerve terminals which also contained numerous small vesicles. Atrial natriuretic peptide immunoreactivity occurred exclusively in myocardial cells where it was localised to large secretory vesicles. The human atrial appendage comprises a neuroendocrine complex of peptidecontaining nerves and myocardial cells producing ANP.     

Changes in the ultrastructural organization of Pseudomonas aeruginosa cells as affected by sodium dodecyl sulfate

The work was aimed at studying the effect of sodium dodecyl sulfate (SDS), an anionic surfactant, on the fine structure of Pseudomonas aeruginosa IC cells capable of its destruction and on the fine structure of P. aeruginosa 1C-16 cells which could not cause the degradation of this surfactant.     

The ultrastructural organization of Brucella L forms and revertant cultures

The submicroscopic organization of Brucella cells in the process of L-transformation and reversion has been studied. As revealed in this study, at its initial stages L-transformation is accompanied by the loss of cell-wall peptidoglycan and by considerable polymorphism of Brucella cells. Further stages are characterized by the presence of a great number of closed annular membrane structures both in the cytoplasm and outside the cells. At late stages of L-transformation the destruction of the cytoplasm and the cells has been found to occur. In revertant cultures the restoration of the cell wall has been noted.