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Annulate lamellae in the pineal organ of a tinamid bird.
This study reports the occurrence of annulate lamellae in the rudimentary photoreceptor cells of the pineal organ of a tinamid bird Crypturellus parvirostris. The annulate lamellae observed in these cells are located in the cell body and are comprised of 1 to 8 parallel lamellae, symmetrically aligned and regularly spaced. Each lamella consists of pairs of parallel membranes interrupted by regularly spaced pores or annuli. These observations are discussed and compared with the structure and distribution of these organelles referred in the literature.
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Ultrastructural observations in Parkinsonism.
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The trigeminal mesencephalic nucleus. II. Electron microscopy.
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Subsurface cisterns and lamellar bodies in the granule cells of the guinea-pig fascia dentata.
Subsurface cisterns (SSC's) and less frequent lamellar bodies (LB's) were identified in the granule cells of the guinea-pig fascia dentata. Both structures, composed of flattened or collapsed agranular cisterns, are continuous with the regular rough endoplasmic reticulum and occasionally connected with each other forming LB-SSC complexes. The SSC's are apposed to glia, synaptic boutons, and nerve cell processes as well as to neighbouring granule cells appearing here singly and in confronting pairs. The quantitative analysis of the various cisternal appositions compared to the distribution of the tissue components on the granule cell soma shows that the overwhelming majority of SSC's are related to glial cells.
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[Cilia-centriole-Golgi apparatus relationships in the glandular cells of the anterior pituitary of the hedgehog (Erinaceus europaeus L)].
Antehypophysial somatotropic and prolactinic cells of the Hedgehog have isolated cilia composed by a ring of 9 or 8 double tubules with or without a central tubule; this single cilia is in relation with a basal corpuscule. A granulo-filamentous neck joins the basal corpuscule to the subjacent centriole; from this granulo-filamentous neck accompanying the complex basal corpuscule-centriole, microtubules and striated filaments extend towards the Golgi apparatus. The single cilia, probably of chemoreceptor significance, appears in relation with the Golgi complex, a zone of granule formation.
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The pineal gland of equatorial mammals. I. The pinealocytes of the Malaysian Rat (Rattus sabanus).
The ultrastructure of the pinealocytes of the Malaysian rat (Rattus sabanus), a mammal inhabiting a zone near the equator where the annual variations of daylength are inconspicuous, was examined and compared with that of pinealocytes of other mammals. On the basis of the presence of granular vesicles, only one population of pinealocytes was found. A large number of granular vesicles and vesicle-crowned rodlets is characteristic of the pinealocytes of this equatorial species. Vesicle-crowned rodlets are especially numerous in the endings of the pinealocyte processes and; they most often found in direct topographical connection with the perivascular spaces. The physiological significance of the presence of such large amounts of vesicle-crowned rodlets and of the secretory process characterized by the formation of granular vesicles is discussed.
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Cerebrospinal fluid-contacting area in the pineal recess of the vole (Microtus agrestis), guinea pig (Cavia cobaya), and rhesus monkey (Macaca mulatta).
The ventricular lining in the pineal recess of the vole (Microtus agrestis), guinea pig (Cavia cobaya) and Rhesus monkey (Macaca mulatta) was investigated light and electron microscopically. Deep in the pineal recess of all three species the ependymal lining exhibits interruptions. A varying proportion of pinealocytes penetrates through this ependymal area, so that the surface of the protruding cells is directly exposed to the cerebrospinal fluid (CSF). At their base, these cells are anchored in the hypependymal tissue by means of processes. It is conjectured that these pinealocytes are engaged in secreting pineal substances into the CSF, as various physiological findings appear to indicate.
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Influence of light and darkness on the ultrastructure of the pineal organ in the blind cave fish, Astyanax mexicanus.
Ultrastructural changes of the pineal organ were investigated in the blind cave fish, Astyanax mexicanus, kept under continous artificial light (5000 lux), in continuous darkness, and under natural light conditions. The pineal end-vesicle of the fish kept under natural photoperiod consisted of photoreceptor cells and supporting cells mixed with a few ganglion cells. The photoreceptor cells possessed well-developed outer segments with regularly arranged lamellar membranes. The supporting cells contained a number of lipid droplets and large globular cisternae filled with fine granules. In the fish kept under continuous light or in darkness, the pineal end-vesicle displayed a dilated lumen, and the outer segments of the receptors showed signs of degeneration. Furthermore, alterations of cell organelles were observed in the photoreceptor and supporting cells.
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On the presence of conspicuous electron dense bodies in the pinealocytes of the pig.
The pinealocytes of the pig contain a large number of aldehydefuchsin positive granules. In order to determine their nature an ultrastructural study was carried out. Numerous bodies having a maximal diameter of about 1,600 nm were found. These elements showed a great variety of internal structure, ranging from a "homogeneous" content and amorphous dense aggregates to lamellate bodies. Although only a few of them displayed a positive reaction for acid phosphatase, their morphological appearance strongly suggests that they belong to the lysosomal system.
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Structural changes induced in capillary endothelial cells by growth factors: altered distribution of cytoskeletal elements and organelles in cells spreading in the presence of tumor conditioned medium and hypothalamus derived growth factor.
Using high-voltage and conventional electron microscopy of cell whole mounts, we have investigated the effects of tumor-conditioned medium and hypothalmus-derived growth factor on the structure of capillary endothelial cells during their attachment and spreading in tissue culture. Cells were cultured in A, Dulbecco's Modified Eagle's Medium (DMEM) and 10% calf serum; B, equal parts of A and 48 hr mouse sarcoma conditioned medium; and C, A containing 10 units of hypothalamus-derived growth factor. Cells cultured in all three media were fully spread, and to the same extent, by 4 hr after plating. While spreading, cells cultured in DMEM alone developed prominent stress fibers and contained numerous bundles of microtubules which formed radical tracts along which mitochondria and other organelles rapidly moved to the cell periphery. Stress fibers were thinner and microtubule tracts fewer in number in cells cultured in tumor-conditioned medium. In 4 hr, organelles moved only part of the distance to the cell margin. Stress fibers were rudimentary and microtubules randomly orientated in cells exposed to hypothalamus-derived growth factor. Most organelles remained near the cell nucleus. The dramatic decrease in stress fibers and microtubule tracts in cells grown in tumor-conditioned medium and hypothalamus-derived growth factor and the subsequent decreased capacity of the cells to move organelles toward their periphery could have some functional significance relative to the growth-promoting activity of these substances.