Cisternae Of Smooth Endoplasmic Reticulum Research Articles

Two subcompartments of the smooth endoplasmic reticulum in perisynaptic astrocytic processes: ultrastructure and distribution in hippocampal and neocortical synapses

Perisynaptic astrocytic processes involved in the tripartite synapse functioning respond to its activation by local depolarization with calcium release from the intracellular stores inside nodes of astrocytic processes and develop local and generalized calcium events. However, based on the first electron microscopy studies a point of view was formed that terminal astrocytic lamellae are devoid of any organelles, including the main astrocytic calcium store - the cisternae of the smooth endoplasmic reticulum. Indeed, analysis of smooth endoplasmic reticulum cisternae could be limited by their weak electron contrast, the studying of astrocytic processes on single sections, and insufficient optical resolution of the equipment used. Here, by using serial section transmission electron microscopy and 3D reconstructions, we analyzed astrocytic processes in murine hippocampal and cortical synapses. As a result of unit membranes contrast enhancement, it was shown for the first time that perisynaptic processes of astrocytes with a morphology of thin branchlets contain two types of smooth endoplasmic reticulum cisternae and microvesicles. Unlike branchlets, membrane organelles inside terminal lamellae were comprised by only short fragments of thin smooth endoplasmic reticulum cister-nae and microvesicles, whose groups tend to be located in close proximity to active zones of the most active synapses. We speculate both on reliability of the alternative methods in electron microscopy while studying astrocytic microenvironment of synapses and structure-function aspects of smooth endoplasmic reticulum cisternae compartmentalization inside the perisynaptic processes of astrocytes.

Effect of ozone versus naringin on testicular injury in experimentally induced ulcerative colitis in adult male albino rats

ABSTRACT Testicular dysfunction is caused by the continuous inflammation and oxidative stress that are present at the local site in ulcerative colitis (UC) spreading to the testes via systemic circulation. The influence of ozone and naringine on colitis-mediated testicular dysfunction was investigated in this study. Forty-eight adult male rats were divided into four groups: I control group, II dextran sodium sulfate (DSS) UC-induced group, III DSS+naringine, and IV DSS+ozone groups. UC was induced in groups II, III, and IV using 0.1 ml of 4% DSS in their drinking water per day for 6 days by gastric gavage. All animals were sacrificed 45 days from the start. Blood samples were obtained to estimate serum testosterone hormone. Testicular tissues were processed for measurement of tissue malondialdehyde (MDA) and examined by light and electron microscopes. Ultrastructurally, group II revealed a relatively thick basement membrane enveloping the seminiferous tubule. Sertoli cell cytoplasm appears rarified with wide intracellular spaces, vacuoles, and multiple lysosomes; distorted spermatogonia with electron dense nuclei and cytoplasm; and primary spermatocytes with small nuclei and electron dense cytoplasm. Abnormal sperm profiles were visible in middle pieces, mid, principle, and end pieces that were markedly affected with disorganization of axoneme and outer dense fibers. Leydig cells revealed dilated cisternae of smooth endoplasmic reticulum. Morphometric and statistical analyses were performed. Group III showed some improvement; however, group IV showed more improvement. The results indicated that ozone caused marked improvement than naringine against UC-induced testicular damage via their antioxidant and anti-inflammatory properties.

Qualitative and Quantitative Study of the Changes in the Ultrastructure of Mammalian Adrenal Cortex Caused by the Venezuelan Tigra Mariposa (Bothrops venezuelensis) Snake Venom.

The damage of the adrenal gland by snake venoms needs to be clarified. Lethality (LD50) of Bothrops venezuelensis (Bv) venom was established by intraperitoneally mice injections. Preparation of specimens for transmission electron microscopy samples from cortex adrenal gland biopsies at 3, 6, and 24 h was processed. The quantitative description by the principal component analysis (PCA) of the adrenal gland was as follows: thickening of the capillary endothelium, area of the capillary lumen, cell nucleus area, enlargement of the perinuclear space, number of mitochondria, area of the mitochondria, number of mitochondrial cristae, number of cristae per mitochondrial unit, and tubular diameter of the smooth endoplasmic reticulum (SER). Sections of the adrenal cortex, after 3 h postinjection with Bv venom showed in the cortical cells: mitochondria with tubular cristae and slightly swollen SER cisternae, nucleus with variable heterochromatin content, irregular edges, and swollen nuclear envelope. After 6 h, cells with swollen nucleus envelope, electron dense lipids and mitochondria with loss of their cristae were observed. Myelin figures, close to the microvilli of the cortical cell, multivesicular bodies, swollen profiles of the SER, and electron dense lipid drops were noticed. After 24 h, thickening of the endothelial wall, fenestrae and projections into the capillary lumen, loss of the mitochondrial cristae, destruction of the capillary and the plasma membrane of the cortical cell, multivesicular body, SER loss, and an enlargement of the perinuclear space were detected. In the quantitative PCA, there were significant changes after the venom treatments.

Efficacy of gold nanoparticles against isoproterenol induced acute myocardial infarction in adult male albino rats

ABSTRACTThis study was undertaken to investigate the role of gold nanoparticles (GNPs) of 50 nm diameter on isoproterenol (ISO) induced acute myocardial infarction in adult male albino rats. Forty five adult Wistar male albino rats were equally divided into three groups. Control (group I) was further subdivided into three subgroups. In group II, the rats received ISO subcutaneously at a dose of 100 mg/kg for three days. In group III, rats received ISO as group II and then GNPs (400 μg/kg/day) intravenously for 14 consecutive days. Echocardiography was performed. Left ventricular specimens were prepared for H&E, van Gieson staining, immunohistochemical analysis for (eNOs and Bcl-2), and Electron microscope examination. Energy dispersive X-ray microanalysis was also performed. Cardiac markers such as creatine Kinase-MB (CK-MB), alanine aminotransferase (ALT), aspartate aminotransferase (AST), and cardiac troponin T (cTnT) were measured. Group II revealed cardiomyocytes with deeply stained acidophilic cytoplasm, small dark nuclei, intracellular vacuolations, wide intercellular spaces, and extravasated red blood cells. Increased collagen fibers were observed. Electron microscope examination showed cardiomyocyte with small and irregular outlined nuclei, mitochondria with irregular cristae and others with ruptured mitochondrial membrane, abnormal alignment of myofibrils, dilated cisternae of smooth endoplasmic reticulum, and disorganized intercalated discs. Group III showed that most cardiomyocytes preserved the normal architecture. Increased expression of eNOs immunoreaction and decreased Bcl-2 immunoreaction were detected in group II as compared to the control and GNP-treated groups. These findings suggested that GNPs of 50 nm diameter improved myocardial injury after ISO-induced myocardial infarction in rats.Abbreviations: Myocardial infarction (MI), Isoproterenol (ISO), Nitric oxide (NO), Neuronal NOS (nNOs), Endothelial NOs (eNOs), Gold nanoparticle (GNPs), Diamiobenzidine (DAB), Serum Creatine Kinase-MB (CK-MB), Alanine aminotransferase (ALT), Cardiac troponin T (cTnT), Electrochemiluminiscence (ECLIA), Cardiomyocytes (CMC), Peroxisomal proliferator activated receptor (PPARs), Reactive oxygen species (ROS)

Changes in Pinealocytes type I and II of Adult Albino Rat Exposed to Different Wavelengths of Light or Confined to Constant Darkness: A Morphological and Electron Microscopic Study

Introduction: the pineal gland is a neuro-endocrine gland that secretes melatonin hormone whichregulates the circadian rhythm, psychiatric disorder and age changes resulting from exposure to differentlight wavelengths or darkness. Intensity, duration and wavelength of light control the activity of pinealgland.Aim of work: the purpose of this study was to monitor the morphological and electron microscopicchanges in the pinealocytes type I and II of albino rats exposed to either constant (24hrs/day) red light(long wavelength) or blue light (short wavelength) as well as confined to constant darkness as comparedto control group subjected to normal diurnal conditions.Material and methods: forty adult male albino rats were divided into four subgroups. Group I (GI):the rats were kept under normal diurnal conditions, group II (GII): the rats were confined to constantdarkness, group III (GIII): the rats were exposed to constant red light (long wavelength; 670nm) andgroup IV (GIV): the rats were subjected to constant blue light (short wavelength, 450nm); for four weekscontinuously.Results: morphological findings of pinealocytes type I (PI) were analyzed statistically and revealed anincrease in the nuclear number of PI in GII, decrease in the nuclear number of PI in GIV and nonsignificantdifference in nuclear number of PI in GIII as compared to the control group. In addition,rats of GIV reported a statistically significant increase in the amount of collagen fibers between looselypacked parenchymal cells. Electron microscopic results of the cytoplasm of PI in GII showed abundantcell organelles such as mitochondria, numerous ribosomes and multiple lipid droplets together withwell-developed Golgi bodies, scarce dense core vesicles (DCV), few cisternae of smooth endoplasmicreticulum (SER) and rough endoplasmic reticulum (RER). GIII demonstrated similar results to that ofGI. On the other hand, GIV showed scarce cytoplasmic organelles such as few mitochondria; mostlydistended with disturbed cristae, scattered lipid droplets with abundant DVC and numerous cisternaeof SER. Ultrastructurally, PI nuclei of GII exhibited infolded nuclear envelope with heterochromatickaryoplasm and prominent nucleoli while GIV revealed reduction of the nuclear chromatin with ruptureof nuclear envelope at certain sites. However, GIII nuclei demonstrated results similar to that of GI. Noobservable changes were detected by light and electron microscopy of PII in the different experimentalgroups apart from the presence of statistically significant increase in the nuclear number of PII in GII.Moreover, the PII cytoplasm showed scarce mitochondria in GI, II and RER in GIV. The glial cellsdemonstrated statistically significant increase in GIV but non-significant differences were noticed in theother groups as compared to GI.Conclusion: it could be concluded that the morphological and electron microscopic changes ofpinealocyte type I indicate decrease in the activity of pinealocytes type I on exposure to constant shortwavelength blue light and increase in the activity of PI confined to constant darkness. While the exposureto constant long wavelength red light demonstrates results similar to the control group. There were nochanges in the structure of pinealocytes type II in the different experimental groups, exposed to differentlight wavelengths or confined to darkness.

The unusual spermatozoa ofDolichodasyssp. (Gastrotricha, Macrodasyida)

Abstract The spermatozoon of an undescribed species of Dolichodasys (Cephalodasyidae) from the Pacific coast of Panama was studied at structural and ultrastructural levels. Under optical microscopy, it appears as a short and wide cell with pointed extremities but without a flagellum. The cell body is made up of two well distinct regions: an anterior region with a homogeneous appearance, and a posterior region containing an evident rod-like nucleus. Under TEM, a peripheral layer of microtubules densely arranged extends for the whole cell length. In the anterior cell region, microtubules surround many tubular cisternae of smooth endoplasmic reticulum (SER), and a thin layer of vesicles with a probable acrosomal function lies just beneath the plasma membrane. The rod-shaped nucleus fills up the posterior cell region and forms a pouch that hosts a single large, irregular mitochondrial mass. A hypothesis about the motility of this aflagellate cell is advanced, on the basis of the coexistence of singlet microtu...

Light and electron microscopic studies on the Y organ of the freshwater crab Travancoriana schirnerae

The fine structure of the premoult Y organ in the freshwater crab Travancoriana schirnerae revealed elliptical epithelial gland cells with large, eccentric, multinucleolated nuclei and ample cytoplasm. The cytoplasm showed numerous polymorphic mitochondria with tubular cristae, highly anastomosed tubules and vesicles of smooth endoplasmic reticulum (SER), rich free ribosomes, small amounts of cisternae of rough endoplasmic reticulum (RER), microtubules and was devoid of Golgi complexes. Mitochondria were of two types the more abundant micromitochondria with electron dense matrix and the less abundant macromitochondria with moderately dense matrix. The tubular SER was particularly concentrated towards the basal region of the cell, intermingled with mitochondria and dense patches of free ribosomes while the vesicular SER lie close to the lateral plasma membrane. Large vesicles with flocculent substances, a few electron dense granules and multivesicular bodies could also be noticed in the gland cell cytoplasm. Aggregations of microvesicles which appeared close to the lateral plasma membrane, in association with dilated SER cisternae and microtubules, possibly suggest the intercellular exchange of substances. The plasma membrane beneath the basal lamina was composed of invaginations and the apical surface possessed numerous microvilli which serve to increase the surface area for metabolic exchange. Towards the apical region, the lateral plasma membrane of adjacent cells was linked by tight junctions. The presence of extraordinarily abundant tubular SER, high proportion of mitochondria with tubular cristae and rich free ribosomes could well be elucidated in favour of steroid production by the gland cells.

Ultrastructural characterization of in vivo-produced ovine morulae and blastocysts.

The ultrastructure of in vivo-produced ovine embryos, at the morula, early blastocyst and late blastocyst stages, was evaluated using transmission electron microscopy. Embryonic cells were characterized by the presence of intact intercellular junctions, numerous mitochondria, smooth endoplasmic reticulum cisternae and light vesicles. Polyribosomes, rough endoplasmic reticulum cisternae, secondary lysosomes, Golgi complexes and lipid droplets were also observed in the cytoplasm. The nucleus was well defined and organized, with an intact envelope rich in nuclear pore complexes, and one or more reticular nucleoli. Microvilli were present in external blastomeres of morulae and became more abundant in trophectoderm cells of early and late blastocysts. Light vesicles seemed to be associated with small cisternae of Golgi and endoplasmic reticulum origin. These cisternae fused and created light vesicles with engulfed heterogeneous cytosolic structures, small cisternae and vesicles. Their labile membrane enabled them to rapidly coalesce into medium-sized vesicles that began to engulf mitochondria and lipid droplets, forming giant vacuoles mostly filled with fat. Incomplete matured secretory vesicles were observed to exocytose into the perivitelline space of morulae, whereas fully matured secretory vesicles appeared only in trophectoderm cells, being exocytosed into the blastocoelic cavity. These observations suggested that these endoplasmic-/Golgi-derived vesicles behave as active autophagic organelles presenting probably a maturation process from compact morulae to blastocyst.

On the Formation of Lipid Droplets in Human Adipocytes: The Organization of the Perilipin–Vimentin Cortex

We report on the heterogeneity and diversity of lipid droplets (LDs) in early stages of adipogenesis by elucidating the cell and molecular biology of amphiphilic and cytoskeletal proteins regulating and stabilizing the generation of LDs in human adipose cells. A plethora of distinct and differently sized LDs was detected by a brief application of adipocyte differentiation medium and additional short treatment with oleic acid. Using these cells and highly specific antibodies for LD-binding proteins of the perilipin (PLIN) family, we could distinguish between endogenously derived LDs (endogenous LDs) positive for perilipin from exogenously induced LDs (exogenous LDs) positive for adipophilin, TIP47 and S3-12. Having optimized these stimulation conditions, we used early adipogenic differentiation stages to investigate small-sized LDs and concentrated on LD-protein associations with the intermediate-sized filament (IF) vimentin. This IF protein was described earlier to surround lipid globules, showing spherical, cage-like structures. Consequently - by biochemical methods, by immunofluorescence microscopy and by electron- and immunoelectron microscopy - various stages of emerging lipid globules were revealed with perilipin as linking protein between LDs and vimentin. For this LD-PLIN-Vimentin connection, a model is now proposed, suggesting an interaction of proteins via opposed charged amino acid domains respectively. In addition, multiple sheaths of smooth endoplasmic reticulum cisternae surrounding concentrically nascent LDs are shown. Based on our comprehensive localization studies we present and discuss a novel pathway for the LD formation.

A histological study on the effect of noise on the adrenal cortex of adult male guinea pigs and the possible role of combined vitamins (A, C, and E) supplementation

Introduction Noise exposure is considered a stressful factor that causes changes in many organs, including the endocrine system. Timing of intervention by antioxidants obviously has a key role in the success of the therapeutic regimen. Aim of the work The aim of the study was to investigate the effect of noise exposure on the histological structure of the adrenal cortex in adult male guinea pigs and evaluate the role of postnoise treatment with vitamins A, C, and E. Materials and methods Thirty adult male guinea pigs were divided equally into three groups. Group I (the control group); group II (the experimental group), which was exposed to noise 4 h/day for 30 days; and group III, which was exposed to noise in the same manner as group II and then administered vitamins A, C, and E once daily for 5 successive days, starting 1 day after noise exposure. Specimens of the adrenal cortex were processed for study by light (H&E stain) and electron microscopy. Morphometric study was also performed. Results The adrenal cortex of the noise-exposed group (group II) showed loss of architecture of the zona glomerulosa and fasciculata with cellular infiltration. In addition, zona fasciculata cells showed marked cytoplasmic vacuolation, whereas zona reticularis cells appeared with condensed nuclei and congested blood sinusoids. Ultrastructurally, zona glomerulosa and fasciculata cells revealed swollen mitochondria, dilated cisternae of smooth endoplasmic reticulum, and a few lipid droplets. Animals treated with combined vitamins (group III) revealed restoration of the normal adrenocortical structure, whereas zona reticularis showed increased proliferative activity. Morphometric study revealed a significant increase in the mean thickness of the cortex and surface area of both zona glomerulosa and fasciculata of the exposed animals, whereas group III revealed nonsignificant difference from the control. Conclusion Exposure to noise caused histological alterations in the structure of the adrenal cortex. Postnoise treatment with vitamins A, C, and E could markedly reduce these alterations.

Morphology, developmental ultrastructure and ultracytochemistry of staminal hairs in Bulbine inflata (Asphodelaceae) in relation to function

Results of light and electron microscopy and preliminary ultracytochemical studies of the staminal hairs of Bulbine inflata at different stages of development are reported here. The staminal filaments are covered with yellow, unicellular, linear, erecto-patent hairs. These staminal hairs arise directly as single cell outgrowths from epidermal cells of the filament. The surface of each hair is patterned with helical wall thickenings in an anticlockwise direction. This wall is covered by a thick folded cuticle, and formed of a loosely fibrillar cellulose layer. The hair cell possesses a cytoplasm rich in organelles. Especially ribosomes are abundant. Plastids contain large starch grains and peripheral lipid droplets. The smooth endoplasmic reticulum cisternae (SER) encircle the plastids and mitochondria; it is extended in the cytoplasm along the hair length. These hairs have functions in flower pollination attracting pollinators visually, secreting specific substances, providing increased surface area, protecting the filaments and being involved in their movement and vibration.

Ultrastructural analysis of the dorsal body gland of the terrestrial snail Megalobulimus abbreviatus (Becquaert, 1948)

The ultrastructure of the reproductive gland, dorsal body (DB), of Megalobulimus abbreviatus was analysed. Electron microscope immunohistochemistry was used to detect FMRFamide-like peptides in the nerve endings within this gland. Nerve backfilling was used in an attempt to identify the neurons involved in this innervation. In M. abbreviatus, the DB has a uniform appearance throughout their supraesophageal and subesophageal portions. Dorsal body cells have several features in common with steroid-secreting gland cells, such as the presence of many lipid droplets, numerous mitochondria with tubular cristae and a developed smooth endoplasmic reticulum cisternae. Throughout the DB in M. abbreviatus numerous axonal endings were seen to be in contact with the DB cells exhibiting a synaptic-like structure. The axon terminals contained numerous electron-dense and scanty electron-lucid vesicles. In addition, the DB nerve endings exhibited FMRFamide immunoreactive vesicles. Injection of neural tracer into the DB yielded retrograde labelling of neurons in the metacerebrum lobe of the cerebral ganglia and in the parietal ganglia of the subesophageal ganglia complex. The possibility that some of these retrograde-labelled neurons might be FMRFamide-like neurons that may represent a neural control to the DB in M. abbreviatus is discussed.

Ultrastructural Organization of the Corpus Luteum of the Indian Emballonurid Bat, Taphozous longimanus (Hardwicke)

The paper describes the ultrastructural organization of the corpus luteum of the emballonurid bat, Taphozous longimanus (Hardwicke). This bat is continuously asychronous breeder, exhibiting aseasonal polyoestry. During the early part of gestation, the luteal cells are compactly arranged with clearly demarcated boundaries, and show only moderate hypertrophy. Ultrastructural study of luteal cells during early pregnancy reveals the presence of irregularly shaped euchromatic nucleus, rod-shaped mitochondria with tubular or vesicular cristae, numerous lipid droplets and profiles of smooth/agranular endoplasmic reticulum in the form of short tubules or vesicles. The close association of mitochondria with lipid droplets and agranular endoplasmic reticulum in the luteal cells suggests that these cells are actively involved in steroidogenesis. During mid-pregnancy, the luteal cells are hypertrophied and are highly vacuolated. Large number of hypertrophied mitochondria, increased profiles of tubular cisternae of smooth endoplasmic reticulum and abundant lipid droplets in the cytoplasm of luteal cells during mid-pregnancy indicate an increase in the steroidogenic activity.

Ultrastructure of sporulation in Haplosporidium armoricanum

An ultrastructural study was carried out on the tissues of an oyster (Ostrea edulis), heavily infected with Haplosporidium armoricanum, that had been fixed in Carson's fixative. The well-fixed tissues revealed details of sporulation and of the spores, which had not been previously reported from H. armoricanum. These include the initial presence of sparse haplosporosomes after thickening of the plasma membrane in early sporonts, division of sporont nuclei by multiple fission, cup-like indentations in the nuclear surface associated with putative nuclear material in both the sporonts and spores, and cytoplasmic multi-vesicular bodies in the cytoplasm of sporonts and spores. The spore wall and operculum were formed from a light matrix that occurred in short cisternae of smooth endoplasmic reticulum in the episporoplasm, and parallel bundles of microfibrils were present in some spores. Spores were rarely bi-nucleate with the nuclei occurring as a diplokaryon, with putative nuclear material at the junction of the 2 nuclei. Nuclear membrane-bound Golgi (NM-BG) cisternae were common in spores, and they appeared to synthesise a light granular material into lysosome-like granules. Dense bodies similar to those reported from H. lusitanicum, H. pickfordi and H. monforti occurred in, or outside, the peripheral endosporoplasm, which was closely apposed to the spore wall. Spore haplosporosomes were frequently axehead-shaped, more like those of H. costale than those previously reported from H. armoricanum, and in some haplosporosomes there was a small round lucent patch with a dark point near the centre of the lucent patch. Overall, H. armoricanum appears to be closely related to H. costale and Bonamia spp. Although the endosporoplasm of H. armoricanum has NM-BG and it resembles the uni-nucleate stage, it appears to be unlikely that they are the same, as the axehead-shaped haplosporosomes of the spore differ considerably from the spherical haplosporosomes of vegetative stages.

Urethral Stromal Tumor with Pacemaker Cell Phenotype

Penile malignancies are rare in developed countries. The authors present a case of a penile urethral mesenchymal tumor occurring in a 51-year-old Caucasian male and displaying light microscopic, immunohistochemical, and ultrastructural features suggestive of a pacemaker cell type, combined with a lack of diagnostic features of any other established tumor category. The immunohistochemical profile was intensely positive for vimentin, PKC θ, and NSE and weakly positive to nonreactive for CD34 and smooth muscle actin, and entirely negative for CD117 (c-kit), S-100, and other markers. C-kit and PDGFRA gene analysis showed no mutations. Electron microscopy revealed tumor cells with plentiful cytoplasm and cytoplasmic processes/filopodia, both filled with intermediate filaments and occasional solitary focal densities. There were also prominent smooth endoplasmic reticulum cisternae, caveolae, neurosecretory granules, particularly concentrated in cytoplasmic processes, and synaptic-type structures. Poorly formed basal lamina, gap junctions, and intercellular collagen aggregates, consistent with skeinoid-type fibers, were also noted. Interstitial cells with potential pacemaker function have been recently described in the lower urinary tract, including the urethra, and this tumor may be related to this cellular phenotype.

Embryo Development in the Lady's Slipper Orchid, Paphiopedilum delenatii, with Emphasis on the Ultrastructure of the Suspensor

Owing to large-scale collecting, the lady's slipper orchid, Paphiopedilum delenatii, is under threat of extinction. Asymbiotic germination provides a useful way to re-establish plants in the wild and for commercial propagation. A detailed study of embryo development would provide information on subsequent germination events and aid in the propagation of the species. Developing capsules were collected for histochemical and ultrastructural studies by using both light and transmission electron microscopy. The suspensor of this species consists of three vacuolated cells. During the early globular stage of embryo development, structural differentiation occurs, revealing an abundance of smooth endoplasmic reticulum cisternae and wall ingrowths within the suspensor cells. These features are not present in cells of the embryo proper. Furthermore, the results of Nile red staining demonstrate that a cuticular layer is present only in the embryo proper, but absent from the suspensor. Cuticular material is also present in the inner walls of the seed coat, and persists through seed maturation. The morphological features of the transfer cell and the absence of cuticular material in the suspensor cell wall corroborate the hypothesis that the suspensor is the major nutrient uptake site for the developing embryo in the lady's slipper orchid. The absence of an endosperm and presence of cuticular material in the inner walls of the seed coat enclosing the embryo proper further support the notion that nutrient uptake by the embryo is confined to the micropylar end of the seed through the suspensor.

In vitro culture on Matrigel favors the long-term maintenance of rat zona glomerulosa-cell differentiated phenotype

Zona glomerulosa (ZG) cells cultured on plastic within few days dedifferentiate losing their capacity to secrete aldosterone (ALDO) in appreciable amounts. Evidence indicates that extracellular matrix modulates the secretory behavior of adrenocortical cells cultured in vitro. Hence, we compared the morphology and function of rat ZG cells grown on plastic and Matrigel basement membrane matrix (hereinafter Matrigel) for up to 12 days. At day 3, no significant differences were observed between cells cultured on plastic and Matrigel. Starting from day 6, ZG cells cultured on plastic lost their ultrastructural differentiated features (mitochondria with tubular cristae, smooth endoplasmic reticulum cisternae and lipid droplets), exhibiting a fibroblast-like appearance. The mRNA expression of the main steroidogenic enzymes, as evaluated by real-time polymerase chain reaction, the baseline secretion of ALDO and other post-pregnenolone hormones, as evaluated by high pressure liquid chromatography, and the secretory response to ACTH, angiotensin-II and K(+), as evaluated by radioimmunoassay, displayed a time-dependent decrease. Matrigel was found to maintain unchanged both the ultrastructure and the expresion of steroidogenic enzymes of ZG cells until day 12 of culture. Baseline and agonist-stimulated steroid-hormone secretion decreased with the duration of culture on Matrigel, but was always higher than that of ZG cells grown on plastic. Hence, our study clearly indicates that the culture on Matrigel favors the maintenance of rat ZG-cell differentiated phenotype, allowing the conclusion that this technique is suitable for long-term in vitro investigations.

Morphologic characterization of rat taste receptor cells that express components of the phospholipase C signaling pathway.

Rat taste buds contain three morphologically distinct cell types that are candidates for taste transduction. The physiologic roles of these cells are, however, not clear. Inositol 1,4,5-triphosphate (IP(3)) has been implicated as an important second messenger in bitter, sweet, and umami taste transductions. Previously, we identified the type III IP(3) receptor (IP(3)R3) as the dominant isoform in taste receptor cells. In addition, a recent study showed that phospholipase Cbeta(2) (PLCbeta(2)) is essential for the transduction of bitter, sweet, and umami stimuli. IP(3)R3 and PLCbeta(2) are expressed in the same subset of cells. To identify the taste cell types that express proteins involved in PLC signal transduction, we used 3,3'diaminobenzidine tetrahydrochloride immunoelectron microscopy and fluorescence microscopy to identify cells with IP(3)R3. Confocal microscopy was used to compare IP(3)R3 or PLCbeta(2) immunoreactivity with that of some known cell type markers such as serotonin, protein gene-regulated product 9.5, and neural cell adhesion molecule. Here we show that a large subset of type II cells and a small subset of type III cells display IP(3)R3 immunoreactivity within their cytoplasm. These data suggest that type II cells are the principal transducers of bitter, sweet, and umami taste transduction. However, we did not observe synapses between type II taste cells and nerve fibers. Interestingly, we observed subsurface cisternae of smooth endoplasmic reticulum at the close appositions between the plasma membrane of type II taste cells and nerve processes. We speculate that some type II cells may communicate to the nervous system via subsurface cisternae of smooth endoplasmic reticulum in lieu of conventional synapses.

Ultrastructural and Immunohistochemical Analysis of Leydig Cells in Patients with Non-Obstructive Azoospermia

Leydig cells are an important source of testosterone, the male sex hormone that stimulates spermatogenesis [1, 2]. These cells are situated in the testicular interstitial compartment, together with blood vessels and other cells of connective tissue. The structural integrity of Leydig cells is necessary for the normal sperm production [3, 4]. The purpose of the study was as follows: 1. to describe ultrastructural changes of Leydig cells in patients with a non-obstructive azoospermia ; 2. to check the testosterone production in situ in testicular biopsies of these patients and 3. to define the levels of this hormone in the blood serum. A total of 60 testicular biopsies from infertile patients with the non-obstructive azoospermia and 8 control biopsies were analysed. In control biopsies, Leydig cells displayed their normal ultrastructure. Round or oval nucleus was situated mostly in the centre of the cell. The chromatin of the nucleus was predominantly euchromatic, with a small presence of heterchromatin associated with the nuclear envelope. A prominent nucleolus was frequently observed. The cytoplasm of the cell was rich in cisternae of smooth endoplasmic reticulum and mitochondria with tubular cristae. Occasional cisternae of rough endoplasmic reticulum, glycogen, lipid droplets and Reinke's crystals were also observed. Leydig cells in infertile men with non-obstructive azoospermia had a significantly changed ultrastructure. The nucleus of such cells was often indented with the increased presence of heterochromatin. Within the cell cytoplasm, a lot of lipid droplets and vacuoles of the electron low-density content could be noticed. There was a reduction in the cisternae of smooth endoplasmic reticulum, glycogen and mitochondria. The presence of Reinke's crystals seemed to be reduced in the pathologically changed cells. However, it should be pointed out that all biopsies contained a limited number of Leydig cells with the normal fine structure. Immunohistochemical analysis (IHC) pointed out a decreased testosterone production in situ (assessed by stereological analysis of IHC positive cells) in testicular biopsies of infertile group. However, when blood serum testosterone levels were considered, 86% of patients with non-obstructive azoospermia had normal testosterone levels. In only 3% of cases testosterone levels were decreased. In conclusion, Leydig cells in patients with the non-obstructive azoospermia displayed a significant change in their ultrastructure. The cells with the normal (unchanged) morphology were also observed within the same biopsies, but were less numerous. IHC data indicated the decreased production of testosterone in situ. However, in the vast majority of cases with non-obstructive azoospermia the peripheral levels of testosterone were normal. Electron microscopic and IHC observations on the fine structure of Leydig cells could help in the understanding of factors contributing to the male-factor infertility.

Mineralization patterns in elasmobranch fish.

This article reviews current findings on the organic matrix and the mineralization patterns in elasmobranchs, including an analysis of the role of the dental epithelial cells and the odontoblasts during odontogenesis. Our electron micrographs demonstrated that tubular vesicles limited by a unit membrane occupied the bulk of the elasmobranch enameloid matrix during the stage of enameloid matrix formation. It is likely that the tubular vesicles originated from the odontoblast processes. Two types of electron-dense fibrils, with cross-striations at intervals of approximately either 17 nm or 55 nm, respectively, were detected in the enameloid matrix. These data suggest that odontoblasts were strongly involved in enameloid matrix formation and in initial enameloid mineralization. Two types of odontoblasts, dark and light cells, were recognized during the stage of dentinogenesis. The light cells contained numerous mitochondria, intermediate filaments, and microtubules that extended their processes into the dentin. The dark cells possessed a well-developed Golgi apparatus and many cisternae in the rough endoplasmic reticulum, which suggests that the dark cells are involved in the formation of dentin. The inner dental epithelial (IDE) cells exhibited a well-developed Golgi apparatus, many mitochondria, cisternae of smooth endoplasmic reticulum, vesicles, vacuoles, and granules during the mineralization and maturation stages. During the stages of mineralization and early maturation, ACPase-positive granules were visible in the IDE cells and ALPase and Ca-ATPase activities were found at the lateral and proximal cell membrane of the IDE cells, suggesting that the IDE cells are involved in the removal of enameloid organic matrix and in the process of mineralization during later stages of enameloid formation. Our data indicate that elasmobranch enameloid is distinct from teleost enameloid, based on its organic content, on the mechanisms of its mineralization, and on the role of IDE cells concerning enameloid formation.