Showing papers on "Ultrastructure published in 1969"

THE ULTRASTRUCTURE OF THE CAT MYOCARDIUM: I. Ventricular Papillary Muscle

Abstract: The ultrastructure of cat papillary muscle was studied with respect to the organization of the contractile material, the structure of the organelles, and the cell junctions. The morphological changes during prolonged work in vitro and some effects of fixation were assessed. The myofilaments are associated in a single coherent bundle extending throughout the fiber cross-section. The absence of discrete "myofibrils" in well preserved cardiac muscle is emphasized. The abundant mitochondria confined in clefts among the myofilaments often have slender prolongations, possibly related to changes in their number or their distribution as energy sources within the contractile mass. The large T tubules that penetrate ventricular cardiac muscle fibers at successive I bands are arranged in rows and are lined with a layer of protein-polysaccharide. Longitudinal connections between T tubules are common. The simple plexiform sarcoplasmic reticulum is continuous across the Z lines, and no circumferential "Z tubules" were identified. Specialized contacts between the reticulum and the sarcolemma are established on the T tubules and the cell periphery via subsarcolemmal saccules or cisterns. At cell junctions, a 20 A gap can be demonstrated between the apposed membranes in those areas commonly interpreted as sites of membrane fusion. In papillary muscles worked in vitro without added substrate, there is a marked depletion of both glycogen and lipid. No morphological evidence for preferential use of glycogen was found.

Ultrastructure and functioning of the transport system of the leguminous root nodule.

Abstract: The structure of the vascular tissues of nitrogen-fixing nodules of 27 genera of legumes and some non-legumes has been investigated by light microscopy. Pisum and Trifolium nodules have been examined by electron microscopy. Attention is directed to the presence of a pericycle in the vascular bundles of the nodules. In 7 of the legumes the pericycle cells possess a wall labyrinth consisting of branched filiform protuberances. The ultrastructure of the pericycle cell cytoplasm is described: its most striking feature is its abundant rough endoplasmic reticulum. These cells surround the xylem and phloem of the bundles, and are in turn surrounded by a layer of endodermal cells with Casparian strips. The pericycle cells develop their wall labyrinth in the levels of the nodule at which the bacterial tissue becomes pigmented; in nodule senescence their cytoplasm is disrupted level with the breakdown of the bacterial tissue. A pathway for symplastic lateral transfer of assimilates exists, from the sieve elements through the pericycle, endodermis and cortex to the bacterial tissue. The apoplast within the endodermis consists largely of the pericycle wall labyrinth and the xylem. The ultrastructure of the Casparian strip resembles that of roots. Intact, detached nodules can be induced to bleed a fluid from their severed vascular tissue. This fluid is exceptionally rich in organic nitrogen, particularly amides, but does not appear to contain sugars. Comparison between its amino acid composition and that of other parts of the nodule suggests that an active uptake or secretion of nitrogenous compounds precedes export from the nodule. Special functions are suggested for the nodule endodermis and the pericycle cells in this export process.

STUDIES ON THE HUMAN CORPUS LUTEUM I. Observations on the Ultrastructure of Development and Regression of the Luteal Cells During the Menstrual Cycle

Abstract: The ultrastructure of huma corpora luntea obtained approximately 2, 3, 5, 11, and 15 days after ovulation is reported. All specimens were fixed in Karnovsky's formaldehyde-glutaral-dehyde solution. The 5-day corpus luteum is presumed to represent, in terms of fine structure, the ultrastructural aspects of high progesterone production and is compared to younger differentiating and older regressing specimens. A distinct topographic relationship of cytoplasmic organelles is noted in the mature 5-day luteal cell. It consists of a peripheral cupshaped mass of tubular ER (endoplasmic reticulum), associated with granular ER, lipid droplets, and mitochondria, which merges with a large paranuclear Golgi area extending to a cell surface bordering a perivascular space. The plasma membrane of active luteal cells is described and its variations suggest areas of specialized surface activities. The prevalence and ultrastructure of more electron-opaque stellate cells, of phagocytes, and of thecal cells are reported.

An electron microscopic study of the early changes proximal to a constriction in sympathetic nerves

Abstract: The ultrastructural changes, proximal to a constriction, in unmyelinated postganglionic sympathetic axons have been studied in the cat splenic and hypogastric nerves. They were constricted with a fine ligature, which was left in situ, and examined at intervals up to 24 h after operation. Immediately after tying the ligature there were definite changes in the morphology and organelle content of the axons adjacent to the constriction. These were due to the mechanical trauma produced by tying the ligature. From 10 min onwards there was a rapid accumulation of organelles in axons, which became progressively more swollen. Eventually the plasma membranes of both axons and Schwann cells broke down and later the Schwann cell basement membrane ruptured, allowing axonal organelles to escape into the interstitial spaces. The accumulating organelles included vesicles with an electron dense core, mitochondria, large vacuoles and myelin figures. Filamentous structures and both fine and wide tubules were more prominent and more numerous after operation. These were accompanied by a marked increase in the number of agranular vesicles. Tubular structures, morphologically similar to both the agranular vesicles and the vacuoles, were also very numerous. This similarity in appearance and the fact that many of these agranular vesicles, vacuoles and tubules were found joined together by either filaments or fine tubules suggests that they are part of the same system. At all times the greatest accumulation of organelles and the most marked axonal swelling was found in the first 0$\cdot $5 to 1 mm segment of nerve immediately adjacent to the constriction. Less marked changes, affecting principally the agranular vesicles and finer tubules together with focal accumulations of mitochondria were seen at more proximal levels from 4 h onwards. It is suggested that the axonal swelling is due to the accumulation of axoplasm and organelles. Two possible interpretations are discussed: (1) that this represents the effects of obstructing the normal flow of axoplasm from the cell body to the periphery, and (2) that some features, in particular the increase in the size and number of the various tubules may be indicative of an active reaction to the effects of axonal injury. These two phenomena probably take place simultaneously and are accompanied by degenerative changes.

The paranucleolar structure, accessory body of Cajal, sex chromatin, and related structures in nuclei of rat trigeminal neurons: a cytochemical and ultrastructural study.

Abstract: Comparative light and electron microscopic study of nuclei in rat trigeminal neurons identified two structures which are the ultrastructural equivalent of the paranucloelar structure and the accessory body of Cajal, two nucleoplasmic structures previously demonstrated in other neurons by light microscope silver staining methods. Ultrastructural evidence indicates that the dense component of the nucleolus is converted into the paranucleolar structure, which then detaches from the nucleolar surface to lie free in the nucleoplasm as the accessory body of Cajal. The cytochemistry, ultrastructure, and antimonate reactivity of the paranucleolar structure and accessory body were identical. Both structures lacked cytochemically demonstrable DNA, RNA, or basic protein. The neuronal nuclei also contained Feulgen-positive sex chromatin bodies that adhered to the nucleolus, the nuclear membrane, or to both of these structures in specimens of female but not male rats. The ultrastructure and antimonate reactivity of these bodies closely resembled that of heterochromatin clumps but differed markedly from that of the paranucleolar structures and accessory bodies. Additional structures characterized ultrastructurally included patches, granular bodies, and flakes. These structures, like the paranucleolar structure and the accessory body of Cajal, are apparently unique to nuclei of neurons. Cytochemical methods showed that the patches contained basic protein but no nucleic acid.

Notes on the ultrastructure and sporoblast development in fish parasitizing myxosporidian of the genus Sphaeromyxa.

Abstract: The ultrastructure of trophic stage (plasmodium), spore and changes in fine structure during morphogenesis of the spore were studied by electron microscopy in two representatives of the genusSphaeromyxa Plasmodium has a highly differentiated structure; there is an outer layer of homogeneous plasm, the endoplasm consisting of a vacuolated mass in which “float” generative cells and sporoblasts in different degree of development Generative cells have well developed pseudopodia Sporoblasts arise from the union of two cells, out of which the inner one forms all cells of the spore, the outer one has only an enveloping function Polar capsule develops in a way identical with other myxosporidia; the wide filament, however, has a longitudinally folded structure and is located within the capsule in two loose loops The mitochondria of an early sporoblast are characterized by a high content of DNA The identity of polar capsule development with the nematocyst morphogenesis is too conspicuous to be taken for a mere convergence Studies on ultrastructure give no evidence for a protozoan character of myxosporidia; together with other findings, they are in favor of the nonprotozoan nature of this group of organisms

Ultrastructure and Sequential Development of Infectious Pancreatic Necrosis Virus

Abstract: The morphology and sequential development of infectious pancreatic necrosis (IPN) virus, a pathogen of trouts, were studied by electron microscopy Mature virions were seen in the cytoplasm of infected cells incubated at 24 C as early as 6 hr after infection These virions were hexagonal in profile and approximately 55 nm in diameter Generally between 8 to 10 hr after infection, virus crystals of various sizes were occasionally observed Although virus replication did not appear to be confined to a particular cytoplasmic locus, mature virions were sometimes seen in association with unidentified tubular structures approximately 45 nm in outside diameter Negative stains of virus revealed unenveloped icosahedra approximately 65 nm in diameter with probably 92 capsomeres Contrary to a previous communication which reported IPN virus to have picornavirus-like morphology, we found it to morphologically resemble members of the reovirus group

Studies on the human corpus luteum. II. Observations on the ultrastructure of luteal cells during pregnancy.

Abstract: The ultrastructure of human corpora lutea obtained during the 6th, 10th, 16th, and 35th week of pregnancy is reported. Differences between the established luteal cell of pregnancy and the transitory luteal cell of the menstrual cycle are noted. In pregnancy the luteal cell is more compartmentalized into a peripheral mass of ER (endoplasmic reticulum) and a central area where mitochondria and Golgi complexes are concentrated. The latter area extends to a cell surface where microvilli face on a perivascular space. Long bundles of filaments are prominent within the luteal cell cytoplasm and, in contiguous cells, appear to arise from adjacent desmosomal regions. Bilateral subsurface cisternae of granular ER at lateral cell borders appear to be areas of specialized junctional surfaces. Certain luteal cells with irregular nuclear membranes are also characterized by vesicular aggregates enclosed within a single membrane. These aggregates are found within the peripheral nucleoplasm or the perinuclear cytoplasm. Their single limiting membrane often appears continuous with either the inner or outer leaflet of the nuclear membrane.

Cortical ultrastructure of Paramecium aurelia. Studies on isolated pellicles.

Abstract: Two methods have been devised for the isolation of large quantities of purified pellicles (cortical layers) of Paramecium aurelia. Pellicles isolated by both procedures, when examined by electron microscopy, were found to contain ciliary basal bodies, two types of cortical membranes, ribbons of microtubules, kinetodesmal fibers, and elements of the infraciliary lattice system. By electron microscopy, the extent of preservation of the various cortical structures when pellicles are isolated by each method has been characterized. Pellicles isolated in both ways have been utilized to investigate cortical morphology of Paramecium. Both phase-contrast and electron microscopic observations have been made. Many new ultrastructural features were observed and are reported herein. An interesting result of this study is the discovery in stock CD that the structure of cortical territories (the territory is the functional unit of cortical morphogenesis and physiology) may vary within a single organism. Features which show variation include number of parasomal sacs, microtubular ribbons, and basal bodies (and therefore cilia) per territory, number of microtubules per ribbon, and length of kinetodesmal fibers. The possible significance of these variations, with respect to territory replication, is discussed. In addition, preliminary observations on the solubility of various cortical organelles in the presence of a number of protein-denaturing agents are reported.

A comparative study of the ultrastructure of resting and active cambium of Salix fragilis, L.

Abstract: Cells of the resting cambium contain vesiculate smooth endoplasmic reticulum, free ribosomes, oil droplets, and protein bodies. There are comparatively few vacuoles, and these are small. The nucleus is fairly central within the cell and is surrounded by a cluster of plastids and mitochondria. Active cambial cells and young differentiating xylem elements are highly vacuolate, contain rough endoplasmic reticulum and polyribosomes, the Golgi apparatus is active in the production of vesicles, and the distribution of organelles is a function of the vacuolation of the cell.

Ultrastructure of the Human Tympanic Membrane

Abstract: In order to arrive at a better understanding of the aetiology and patho-genesis of middle-ear diseases through basic knowledge concerning the electron microscopic appearances in the normal middle ear, a study of the ultrastructure of the human tympanic cavity has been instituted in our Laboratory. The preparations for the present study were fixed from 55 min to 4 hours post mortem Fixation later than 3 hours post mortem resulted in structural autolytic damage. The tympanic membrane consists of three layers: the epidermis whose ultrastructure was found to correspond to the findings in the epidermis of normal skin, the lamina propria containing loose connective tissue, vessels, nerves, and two layers of collagen fibrils (also in the pars flaccida), and the lamina mucosa. In the pars flaccida the mucosal layer consisted of simple squamous cells with microvilli. All through the pars tensa there were cells of varying height, often pseudostratified columnar cells with a large number of cilia and secretory granu...

The ultrastructure of stellate cells in the pars distalis of the salamander pituitary gland

Abstract: The ultrastructure of a distinct cell type, termed the stellate cell, in the pars distalis of the salamander (Triturus [Notophthalus, Diemyctylus] viridescens viridescens) pituitary gland is described. The cell has three primary characteristics which distinguish it from other cell types of the pars distalis: (1) a lack or sparsity of specific secretory granules, (2) several cellular processes which are long and sheet-like and (3) cell body and nucleus which are considerably smaller than the cell bodies and nuclei of the chromophilic cells. The stellate cell often has an angular shaped nucleus, and the cytoplasm is characterized by an abundance of glycogen particles, several lipid droplets, an inconspicuous Golgi complex showing no evidence of forming secretory granules, filaments, microtubules and a sparsity of rough endoplasmic reticulum. The cells occasionally contain unusual mitochondria which exhibit longitudinally oriented cristae. From the electron micrographic evidence obtained in this study, it was suggested that stellate cells probably contact all secretory cells in the pars distalis; thus they are favorably situated to play a sustentacular role in the piuitary gland. In addition, the processes of the stellate cell frequently terminate on the outer basal lamina of the pericapillary space. Consideration was given also to a possible secretory role for the stellate cells, but little morphological evidence was obtained to suggest such a function. It was noted, however, that the cells occasionally contain dense bodies about 250 mμ in diameter which were interpreted as possible secretory granules.

Ultrastructure of the mouse tracheal epithelium

Abstract: The ultrastructure of mouse tracheal epithelium was examined. The three cell types, basal cells, ciliated cells and goblet cells, described for other mammalian trachea were found to be present although goblet cells occurred only rarely. A cell type, termed the nonciliated cell, not described in other mammalian trachea was frequently found in mouse tracheal epithelium. These cells contained abundant smooth and rough endoplasmic reticulum, free ribosomes, a large Golgi complex, and many mitochondria. There were many vesciles containing an electron dense material near the luminal surface of these cells; these cells were positive for PAS. These features suggested a secretory function for the cells. This, along with the scarcity of goblet cells, suggested that the nonciliated cells of mouse tracheal epithelium fulfill the function of the goblet cells found in other mammalian trachea.

Ultrastructure of heart muscle under pathological conditions

Abstract: The electron microscope has afforded insight into the ultrastructure of normal heart muscle, making possible a new understanding of the submicroscopical cellular pathology of the heart. This subject has recently been investigated by many research workers with great success. It would be quite impossible to give a comprehensive review of the submicroscopical pathology of the myocardium in this paper; therefore I shall confine myself to my own work, the results of which can be classified as: (1) changes in size and shape of the heart, (2) disorders of the myocardial electrolyte metabolism, and (3) disorders of myocardial energy exchange.

Ultrastructural properties of primary olfactory neurons in fish (Lota lota L.).

Abstract: Qualitative and quantitative aspects of the normal fine morphology of the olfactory receptor cells. their cilia, axons, and neighboring cells, were investigated in the burbot. The receptor cells lacked olfactory tubercles and microvilli; they were isolated from each other by supporting and basal cells. The role of cilia and microvilli in chemoreception was discussed. Zonulae occludentes between the epithelial cells sealed off the interior of the olfactory mucosa of this fresh water animal from an environment with low osmotic activity. The number of receptor cells was estimated to be about 73 per 1,000 μ2. Glial cell processes penetrated from the connective tissue, investing small bundles of receptor axons within the epithelium. Formation of the filum olfactorium was described. The average number of axons in the central portion of the olfactory nerve was about 29 per μ2 in areas free of glial cells and connective tissue. The mean diameter of the axons in the nerve proper was 0.136 μ whereas a higher average was found beneath the epithelium. The presence of mitochondria imparted a considerable skewness to the distribution of diameters. The calculated total number of axons in the olfactory nerve corresponded with the number of receptor cells. The convergence of olfactory nerve fibers upon secondary neurons with myelinated axons was estimated to about 1,000:1.

Fine structure of the paraventricular organ of Xenopus laevis tadpoles.

Abstract: The ultrastructure of the Paraventricular organ in the hypothalamus of Xenopus laevis tadpoles is described. It appeares that the Paraventricular organ of this anuran species is homologous with the Organon vasculosum hypothalami or the Paraventricular organ of other vertebrates. The Paraventricular organ of Xenopus laevis is characterized by an ependymal lining with only few cilia and by two types of nerve cells. Both types of nerve cells have ventricular processes, protruding into the lumen of the third ventricle and forming a network. The protrusions bear cilia of the 8+1 pattern. It has been possible to distinguish both types of nerve cells on account of their dense-core vesicles. A secretory function of both cell types is suggested. In a region close to the Paraventricular organ, another granulated type of nerve cell has been observed. A relationship between these cells and the preoptic nucleus is discussed.

The ultrastructure of egg implantation.

Abstract: What is known of the ultrastructure of normal and experimental implantation as it occurs across a wide variety of species is reviewed. Topics include the ultrastructure of the uterine epithelium and the blastocyst the stages of attachment invasion reaction of the subepithelial tissues and delayed and experimental implantation. The last includes blockade of implantation ectopic and in vitro implantation and interspecific transplantation. Species differences are discussed.