Smooth-surfaced Endoplasmic Reticulum Research Articles

Ultrastructure of epithelial thymic cysts of the chicks.

The medulla of the chick thymus contains variable numbers of intercellular and intracellular cysts. The epithelium varies from squamous to columnar or stratified and contains cystic, endocrine-like, and lymphoid cells. The lumen-lining cystic cells contains microvilli, moderately developed rough- and smooth-surfaced endoplasmic reticulum, and Golgi complex. Mitochondria, free ribosomes, and varying number of microfilaments are observed. Endocrine-like cells are separated from the lumen by the cystic cells, which in places are extremely attenuated. The cytoplasm is characterized by the presence of membrane-limited secretory granules. Cleft-like spaces, partially lined by microvilli, are also encountered. Numerous vesicles, some in tight association with the core rootlets, are evident. Cystic cells with single or multiple cysts, lined with microvilli, are also observed. The lumina of these cystic elements contain flocculent or dense granular material, amorphous masses, cellular elements, or debris. Morphological evidence suggests synthetic and secretory activities of the cystic cells in the young chicks.

The ultrastructure of the giant cell surrounding larvae of Thelazia spp. (Nematoda: Thelazioidea) in the face fly, Musca autumnalis De Geer

The larval nematode, Thelazia spp., initiates a tissue response by the body-wall epidermal cells of its normal intermediate host, Musca autumnalis, resulting in the formation of giant cells. These giant cells differ in several ways from hemocytic capsules: they are larger, lack signs of necrosis, protect the parasite, and represent a true syncytium. Both, however, are considered to be the result of a defensive reaction by the host. Giant cells contain the following organelles which are absent from hemocytic capsules: hypertrophied nuclei, smooth-surfaced endoplasmic reticulum, and annulate lamellae. Further, unlike hemocytic capsules, giant cells lack cell junctions and cytolysosomes. Formation of giant cells is considered beneficial to both the host and the parasite.

X-ray microanalysis and ultrastructural localization of cisplatin in liver and kidney of the rat.

Cisplatin or cis-diamminedichloroplatinum(II) is a platinum coordination compound showing clinically useful antitumor activity, but the major dose-limiting factor is a dose-dependent cumulative nephrotoxicity. At the electron microscopic level, platinum has been localized in the nucleus, microsomes and cytoplasm of cells of the kidney and liver in rats. This report confirms the subcellular localization of platinum and adds one more site of platinum accumulation, the microbody, based on results obtained with an energy-dispersive X-ray microanalyzer (EDX). After daily administration of cisplatin (0.5 mg/ml/kg body weight) successively for 5 weeks, accumulated platinum was detected in microbodies of hepatocytes and epithelial cells of proximal convoluted tubules of the rat. The major site of metal deposition in the kidney was the matrix of many microbodies in the epithelial cells of proximal convoluted tubules. EDX revealed the presence of platinum in those metallic deposits. The matrix of the nucleus also had metallic deposits but they were rather diffuse and platinum could not readily be detected on individual grains in the nucleus. In the liver, major damage was concentrated in hepatocytes, and other types of cells such as Kupffer cells, Ito cells and endothelial cells of capillaries were less affected. Metallic fine grains were localized in the cisterna of smooth-surfaced endoplasmic reticulum and in the matrix of microbodies. The nucleus of hepatocytes had few, if any, metallic precipitates. A specific type of metallic deposition was round aggregations of dense tubules in which platinum was detected by EDX. There was no evidence of platinum precipitation in mitochondria or Golgi complex. These findings suggest that the microbody may play an important role in degradation of the platinum complex both in hepatocytes and epithelial cells of proximal convoluted tubules.

The calcium pump in rat liver endoplasmic reticulum. Demonstration of the phosphorylated intermediate.

Rat liver microsomal fractions enriched with smooth-surfaced vesicles possess an ATP-supported Ca2+ transport activity, which is stimulated by oxalate and half-maximally activated at 3.5 X 10(-7) M free Ca2+. Catalysis of Ca2+ transport involves transient covalent binding of the terminal phosphate from ATP by the vesicles, resulting in the formation of a Mr 118,000 phosphopeptide, which is acid precipitable and unstable in the presence of hydroxylamine, which may be characteristic for an acylphosphate. Phosphorylation of the Mr 118,000 peptide requires the presence of Ca2+, while dephosphorylation is markedly accelerated by Mg2+. In the presence of Ca2+ and Mg2+ phosphorylation proceeds much faster than dephosphorylation, indicating that the latter may be rate limiting for the hydrolysis of ATP. The Mr 118,000 peptide is estimated to represent about 2% of total smooth-surfaced endoplasmic reticulum membrane protein. Comparative studies with sarcoplasmic reticulum from rat skeletal muscle suggest extensive homology of the Ca2+ transport ATPases.

Ultrastructure of feeding sites of the cyst nematode Heterodera schachtii Schmidt in roots of susceptible and resistant Raphanus sativus L. var. oleiformis Pers. cultivars

Ultrastructural changes at feeding sites of the cyst nematode Helerodera schachlii were examined in roots of susceptible and resistant cultivars of Raphanus sativus var oleiformis grown in aseptic nutrient agar culture. Apparently identical changes occurred in both cultivars between 1 and 2 days after invasion by the infective second stage juveniles Induced syncytia (nurse cell systems; derived from parenchymatous cells of the vascular cylinder showed ultrastructural features of high metabolic activity such as a pronounced increase in cytoplasmic density, reduction of the central vacuole into numerous small vacuoles, abundance of ribosonrcs, polyribosotnes, mitochondria, dietyosomes and enlargement of nuclei. Other changes within the syncytia were recorded 3 days after nematode invasion. In the susceptible cultivar there was considerable proliferation of smooth-surfaced endoplasmic reticulum, whereas in the resistant cultivar the endoplasmic reticulum was rough-surfaced with flattened cysternae and there was an incrcrease in vacuolization. Syncytia continued to develop in the susceptible cultivar 4–5 days after nematode invasion, hut disintegrated in the resistant with nearly complete protoplast degeneration 2 days later. Feeding tubes formed by Hardening saliva, were secreted through the stylet aperture of the infective nematode juvenilesinto the initial syncytial cells of both cultivar. The possible function of there tubes for food withdrawal is, discussed.

Characterization of long-term monolayer cultures of human granulosa cells from follicles of different size and exposed in vivo to clomiphene citrate and hCG.

To determine the effects of prolonged hCG treatment in vitro upon granulosa cells from follicles of various sizes previously exposed to clomiphene citrate and hCG in vivo, progesterone and relaxin concentrations of spent media were correlated with light microscopic and ultrastructural characteristics. Intact, freshly dispersed cells were characterized by numerous lipid droplets, elliptical mitochondria with tubular or lamellar cristae, moderate rough-surfaced endoplasmic reticulum (RER), sparse smooth-surfaced endoplasmic reticulum (SER), and few Golgi. After 10-24 days in culture, 2 morphologically distinct cell types, 'granulosa-type' and 'luteal-type', were noted at the light microscopic level. Ultrastructurally, lipid droplets decreased in number, mitochondria became pleomorphic, RER became more prominent and dilated, and Golgi became more widely dispersed. Tubular SER became abundant and annular nexuses became more numerous after hCG treatment in vitro. Granulosa cells generated from all follicles responded to hCG treatment with significantly increased progesterone secretion after 4 days in culture. Relaxin was not detectable in any sample of medium. This study shows that human granulosa cells from 15-25-mm follicles retain their differentiated function of progesterone secretion in long-term culture and recover responsiveness to hCG in vitro, as demonstrated by enhanced progesterone secretion and development of prominent SER and increased annular nexuses.

Bilateral and Extensive Xanthelasma Palpebrarum in a Young Man

A 25-year-old white man had been aware since childhood of yellow discolorations of the medial aspects of his upper lids. The skin changes progressively spread to involve all four eyelids, the inferior skin of the brow, and the lateral and medial canthal skin. The clinical diagnosis was extensive bilateral xanthelasmas. The patient had no manifest abnormality of lipid metabolism, although his father and grandfather had both developed xanthelasmas early in childhood. A snip biopsy of upper lid skin was performed and studied by both light and electron microscopy. The light microscopic appearance confirmed the diagnosis of xanthelasma, in that the upper dermis contained mono- and multinucleated foamy xanthoma cells beset with myriad cytoplasmic vacuoles. Cells displaced outwardly into the interstitium evidenced degradation phenomena within the vacuoles, consisting of lamellar bodies or fingerprint-like inclusions, presumably the result of fusion of lysosomes with the lipidic inclusions. Scattered non-lipidized mononuclear histiocytes with abundant profiles of smooth-surfaced endoplasmic reticulum possibly represented a reserve population of monocytes for conversion into xanthoma cells.

Effects of prolonged antitubulin culture on annulate lamellae in mouse alpha L929 fibroblasts.

The fine structure of alpha L929 fibroblasts cultured in colchicine or vinblastine sulfate for periods as long as 48 hr was compared to control cells not exposed to antitubulins . In response to prolonged antitubulin culture, several changes in cell ultrastructure were noted: Control fibroblasts contain cytoplasmic annulate lamellae (AL), but prolonged exposure to either vinblastine sulfate or colchicine results in enhanced development of AL. Single pore complexes are present in the rough-surfaced endoplasmic reticulum (rER) in both control and antitubulin-treated cells, but stacked porous cytomembranes also occur under both conditions. Polyribosomes often are closely associated or continuous with the pore complexes. Many antitubulin-treated cells become multinucleate. Some nuclei in both control and antitubulin-treated cells contain large and multiple nucleoli. The large and multiple nucleoli are either attached directly to the inner membrane of the nuclear envelope or to infoldings of the nuclear envelope. Antitubulin-treated cells, after 48-hr exposure, appear also to contain enhanced quantities of smooth-surfaced endoplasmic reticulum (sER) and cytoplasmic filaments (and in some cells, lysosomes and rER as well) when compared to untreated cells. In both control and colchicine-treated cells, AL can exhibit continuity with either rER or sER. Further, all three membrane systems may at times be continuous, but the quantity of these membranes appears to be greater in colchicine-treated cells than in control cells. The results are discussed with respect to possible functional significance.

Effects of age and adrenocorticotropin on microsomal enzymes in guinea pig adrenal inner and outer cortices.

Guinea pig adrenals possess a distinctive zona reticularis which increases in volume as the animal matures, coming to occupy over 50% of the gland in mature 800-g animals. The adrenocortical cells of this zone possess abundant smooth-surfaced endoplasmic reticulum. In this paper we demonstrate that microsomes obtained from guinea pig inner cortices of both young and mature animals, consisting predominantly of zona reticularis tissue, possess higher activities of 21-hydroxylase, an enzyme that hydroxylates steroids, and ethylmorphine demethylase, a drug-metabolizing enzyme, as well as higher contents of cytochromes b5 and P450, than microsomes derived from outer cortices, which contain predominantly zona fasciculata tissue. In addition, we show that while the inner cortex contains 90% of the total adrenal activity for ethylmorphine demethylase, ACTH suppresses this activity by 55% and decreases activity in the outer cortex to negligible levels. ACTH does not affect 21-hydroxylase activity or cytochrome b5 or P450 content in either cortical region. These observations suggest that differential regulation of microsomal functions for steroid hydroxylation and drug metabolism occurs largely in the zona reticularis. Furthermore, they suggest that other activities for xenobiotic metabolism, previously reported as a property of whole guinea pig adrenals, may reside in the inner cortex and be unique functions of the abundant smooth endoplasmic reticulum of the zona reticularis cells.

Correlated ultrastructural and morphometric studies on the liver during prenatal development of rats

Quantitative and qualitative changes in liver tissues during prenatal development were studied by electron microscopy and morphometry. On the 15th day, 30% of fetal liver volume consisted of hepatocytes, and the extrahepatocytic spaces amounted to 63%. The hemopoietic cells occupied 93% of the extrahepatocytic spaces. Immature bile canaliculi were observed and amounted only to 0.14% of extrahepatocytic spaces. The hepatocytes were irregular in shape and possessed several large lipid droplets which amounted to 19% of the cytoplasm. Although the rough surfaced endoplasmic reticulum (RER) was well developed, the smooth surfaced endoplasmic reticulum (SER) was not yet differentiated. The typical peroxisomes with nucleoid and glycogen were not observed in the cytoplasm. On the 18th day the volumetric densities of hepatocytes and bile canaliculi were increased. The typical peroxisomes with nucleoid appeared in the cytoplasm. The accumulation of glycogen which amounted to 12% of the cytoplasmic volume had taken place, while the volume of lipid droplets decreased significantly. In glycogen areas the differentiation of SER began. At birth the histogenesis of the liver was well established. The hemopoietic cells decreased in number and were confined to perisinusoidal spaces. The volumes of biliary capillaries and sinusoids were comparable with these of young rats now. The volumetric density of hepatocytes increased and occupied about 74% of the liver. The volumetric densities of mitochondria, SER, peroxisomes, secondary lysosomes, and lipid droplets increased significantly in comparison with those of the 18 days old fetus, while RER, Golgi area, and primary lysosomes were rather constant. The volumetric density of glycogen decreased rapidly at birth.

The membrane association among the rough-and smooth-surfaced endoplasmic reticulum and Golgi apparatus in rat hepatocytes at certain circadian stages.

Subcellular structures of the cytoplasmic components in perilobular hepatocytes were examined at 0500 h and 1700 h in 6 adult male Wistar rats per time period. At both time points, the endoplasmic reticulum (ER) having smooth and rough parts could clearly be observed. Corresponding to the decrease and increase of the smooth-surfaced endoplasmic reticulum (sER) during the 24-hr span, it is thought that the membrane transformation from the sER to rough-surfaced endoplasmic reticulum (rER) at 0500 h and from the rER to sER at 1700 h occurs in the flowing-off of membranes which is accompanied by attachment or detachment of ribosomes. Furthermore, at these time points, the direct continuity of membranes between the rER and Golgi apparatus is discerned. From these findings, it may be elicited that the membrane association among the cytoplasmic components takes an important role in the reorganization of the cytoplasmic components in hepatocytes during the 24-hr span.

The morphology of the amelanotic Greene melanoma.

Pieces of amelanotic Greene melanoma were transplanted onto the iris surface of rabbit eyes, where they started to grow rapidly after a dormant period of four to five days. Light microscopically, the melanoma cells appeared round or polygonal and contained large, lightly staining nuclei and prominent nucleoli. Electron microscopy revealed rather electron translucent nuclei containing only a small rim of heterochromatin immediately subjacent to the nuclear envelope. The very prominent, reticulated nucleoli frequently lay close to the nuclear surface. The cytoplasm of the cells showed a well developed Golgi field which contained myriad vesicles of different shape and density and cross-striated, membrane-bound organelles of early melanin synthesis. The mitochondria were short and the smooth-surfaced endoplasmic reticulum was inconspicuous. The rough-surface endoplasmic reticulum was sparse and exhibited predominantly short segments. Like other very active cells, the melanoma cells contained a multitude of ribosomes. Melanoma cells which were not completely surrounded by other cells exhibited numerous processes at the free cell surface and, directly subjacent to these, a layer of very electron dense cytoplasm, indicating that these cells may possess a certain amount of motility. Many light and electron microscopical aspects of the amelanotic Greene melanoma are identical or similar to human uveal melanomas, especially of the epithelioid variety. On morphological grounds it is therefore possible to suspect a close biological relationship of these tumors. Thus, the use of the Greene amelanotic melanoma as a model for study of diagnostic and therapeutic problems in ophthalmology may be considered adequate.

Circadian alterations in tubular structures on the outer mitochondrial membrane of rat hepatocytes.

Subcellular structures of hepatocytes were examined at 11.00 h and 23.00 h (light cycle: 06.00 h-18.00 h) in four adult male Wistar rats (AF/Han) per time period. 1. The volume density of mitochondria in the cytoplasm of hepatocytes obtained from peripheral parts of liver lobules shows a statistically significant difference between the two time periods examined. 2. Tubular structures arising from the outer mitochondrial membrane are clearly demonstrated. Their cisternae are continuous with the interspaces between outer and inner mitochondrial membranes. 3. These tubular structures often open directly into the cisternae of rough or smooth-surfaced endoplasmic reticulum (rER and sER) and form a "bridge" between the endoplasmic reticulum and mitochondria. 4. At 11.00 h, the rER connected with the tubular structures often possesses very few ribosomes; at 23.00 h, the amount of ribosomes on the rER is substantially greater. Furthermore, at 23.00 h ribosomes are also occasionally found on the membranes of the tubular structures. 5. The incidence of tubular structures on the outer membrane of mitochondria varies significantly between the two time periods. 6. The changing pattern of the volume density of mitochondria in the cytoplasm parallels that of the incidence of the tubular structures, i.e., both are high during the active phase and low during the resting phase of the rat. 7. These results suggest that the tubular structures may play an important role in protein transport between the endoplasmic reticulum and mitochondria, and in the rearrangement of rER during a 24-h period.

Morphological changes of the kidney and bone of rats in chronic cadmium poisoning

Wistar rats were given drinking water containing 200 ppm CdCl 2 for 4 to 91 weeks and the kidneys and femoral bones were examined morphologically. Histological examination showed degenerative changes in the proximal convoluted tubules. Electron microscopically tubular changes consisted of cell edema, swelling of mitochondria, proliferation of smooth-surfaced endoplasmic reticulum, vacuolar degeneration, and coagulative necrosis. These alterations were observed to progress with increase of urinary excretion of protein and cadmium levels in the kidneys. Spontanous nephropathy was found more frequently in cadmium-exposed rats than in controls. The bones showed no significant change in histological and roentgenological examinations, as well as in assay of bone mineral content.

Ultrastructural alterations in the liver of rats fed photomirex (8-Monohydromirex)

Alterations in the liver of rats fed photomirex or mirex for 28 d have been studied by electron microscopy. A dose of 0.05 or 0.5 ppm photomirex produced selective ultrastructural damage to the mitochondria of hepatocytes. The parenchymal cells had a proliferation of smooth-surfaced endoplasmic reticulum (SER) with a concomitant depletion of glycogen, a reduction of rough-surfaced endoplasmic reticulum (RER) profiles, an abnormal accumulation of lipid droplets, and pleomorphic nuclei at the 5 ppm photomirex level. In the animals receiving 50 ppm photomirex there were degenerating foci in the organ. There was an increase of electron-dense bodies in the hepatocytes from the 5 ppm mirex group but these cells, in the animals receiving 50 ppm mirex, had SER proliferation and glycogen depletion. It is concluded that photomirex causes more severe ultrastructural changes in the livers of rats than mirex.

The effect of LH on morphological events of smooth-surfaced endoplasmic reticulum in rabbit follicular oocytes cultured in vitro

The effect of LH on morphological events of smooth-surfaced endoplasmic reticulum in rabbit follicular oocytes cultured in vitro

Age-related changes in liver drug metabolism: structure vs function.

AbstractSeveral definitive statements concerning the effect(s) of animal age on liver drug metabolism are made, and at the same time certain crucial questions that remain to be resolved are posed. Between 16 and 30 months of age, or maturity and senescence, the male Fischer rat exhibits a significant loss of hepatic smooth-surfaced endoplasmic reticulum (SER) which constitutes a real quantitative change. However, this does not exclude the possibility of qualitative age-related changes in this membrane, such as compositional alterations which may be reflected in its functional integrity. Second, there is a significant decline in the noninduced activities or amounts of enzymes and hemoproteins, respectively, of the microsomal mixed function oxidase system. With the exception of the loss of cytochrome P-450, which represents a quantitative change, the age-dependent alterations in the two enzymes may reflect quantitative and/or qualitative changes. Last, the reduced hepatic responsiveness to phenobarbital is ...

Ultrastructure of cell types cultured during preneoplasia from implant surfaces and foreign-body-reactive tissues in mice.

Cell types (I–IV), isolated and expanded in vitro from mouse foreign-body (FB)-reactive capsule tissue or from surfaces of FB segments, were sectioned en face and studied ultrastructurally. The macrophage-like and fibroblast-like nature of respectively, the euploid types I and II cells were substantiated by this ultrastructural study and thus confirmed earlier conclusions that were based on light microscopic morphology and in vitro growth characteristics. Particular emphasis was placed on the characterization and identification of type IV cells in that these aneuploid cells are sarcomagenic when implanted or injected sc into histocompatible recipient mice. The submicroscopic features of the aneuploid type IV cells included: 1) numerous microfilaments (diameter, 6–9 nm); 2) many plasmalemmal (pinocytotic) vesicles; 3) many surface microvilli, ruffles. or blebs; 4) formation of intercellular gap junctions; and 5) relatively extensive smooth-surfaced endoplasmic reticulum and significantly less rough-surfaced endoplasmic reticulum. The much smaller bipolar type III cells had several features in common with type IV cells: 1) an abundance of 6- to 9-nm (diameter) microfilaments, 2) moderate numbers of plasmalemmal vesicles, and 3) many evaginations of the plasma membrane to form microvilli or blebs. A relationship between types III and IV cells was considered likely on the basis of these morphologic similarities and other observations. The submicroscopic features of both types III and IV cells correlated closely with those present in FB-induced sarcoma cells. The specific in vitro characteristics of aneuploid type IV ceUs most closely resembled those of endothelial cells. The results of this study supported the hypothesis that the progenitor cells of FB-induced sarcomas were derived from primitive cells associated with the local microvasculature.

Electron Microscopic Observations of Concentric Lamellar Bodies within Mesenchymal Cells of Anagen Hair Dermal Papilla

The presence of 2 forms of the concentric lamellar bodies was observed in the mesenchymal cells within dermal papilla of normal scalp anagen hairs. They are those composed of agranular membrane arrays in association with beta-glycogen particles (glycogen bodies) and those of smooth-surfaced endoplasmic reticulum (smooth-surfaced lamellar bodies). On rare occasions these 2 forms of the concentric lamellar bodies were simultaneously present within the same cells. Transitional forms between the smooth-surfaced lamellar bodies and phagosegresomal granules were also encountered.

Age-related changes in liver drug-metabolizing enzymes

The non-induced levels of hepatic microsomal NADPH cytochrome c reductase and cytochrome P-450 undergo marked age-dependent declines in male Fischer 344 rats, especially between maturity and senescence. Phenobarbital administration causes significant increases in these two parameters in young and (1 month) and mature (16 months) animals, but not in senescent rats (27 months). Both the rates of enzyme and haemoprotein induction and the maximum-induced levels achieved after six days of drug treatment are significantly greater in the young and mature animals vs the senescent rats. These functional data correlate reasonably well with [1] a similar age-dependent response of microsomal protein concentration to phenobarbital administration and [2] the quantitative morphological evidence demonstrating an age-related loss in the amount of hepatic smooth-surfaced endoplasmic reticulum between maturity and senescence.