Basal Infoldings Research Articles

The potential protective effect of propolis on diabetic nephropathy induced by streptozotocin in adult albino rats

ABSTRACT Diabetes mellitus is a common metabolic disorder. It is associated with serious life-threatening complications if not properly managed. The current study aimed at investigating the possible protective role of propolis on streptozotocin-induced diabetic nephropathy. A diabetic rat model was induced by a single intraperitoneal injection of 55 mg/kg streptozotocin. After 4 days, the diabetic rats received oral propolis (300 mg/kg/day) via gastric gavage for 28 days. Biochemical, histopathological and ultrastructural evaluations were performed. The results showed that: streptozotocin-induced diabetes was associated with a marked decrease in the serum high-density lipoproteins and antioxidant enzymes. However, a significant elevation in the levels of serum creatinine, blood urea nitrogen, uric acid, cholesterol, triglycerides and low-density lipoproteins was detected. Furthermore, streptozotocin treatment induced histopathological alterations of the renal cortex; in the form of distorted glomerular capillaries, widened Bowman’s space and signs of epithelial tubular degeneration. Ultra-structurally, thickening and irregularity of the glomerular basement membrane and podocytes foot processes effacement were observed. The tubular epithelial cells showed swollen vacuolated mitochondria, scarce basal infoldings and loss of microvilli. Conversely, propolis partially restored the normal lipid profile, antioxidant biomarkers and renal cortical morphology. Propolis exhibited a sort of renoprotection through hypoglycemic, anti-hyperlipidemic and antioxidant effects.

Autophagy and Exocytosis of Lipofuscin Into the Basolateral Extracellular Space of Human Retinal Pigment Epithelium From Fetal Development to Adolescence.

To undertake the first ultrastructural characterization of human retinal pigment epithelial (RPE) differentiation from fetal development to adolescence. Ten fetal eyes and three eyes aged six, nine, and 17 years were examined in the temporal retina adjacent to the optic nerve head by transmission electron microscopy. The area, number, and distribution of RPE organelles were quantified and interpreted within the context of adjacent photoreceptors, Bruch's membrane, and choriocapillaris maturation. Between eight to 12 weeks' gestation (WG), pseudostratified columnar epithelia with apical tight junctions differentiate to a simple cuboidal epithelium with random distribution of melanosomes and mitochondria. Between 12 to 26 WG, cells enlarge and show long apical microvilli and apicolateral junctional complexes. Coinciding with eye opening at 26 WG, melanosomes migrate apically whereas mitochondria distribute to perinuclear regions, with the first appearance of phagosomes, complex granules, and basolateral extracellular space (BES) formation. Significantly, autophagy and heterophagy, as evidenced by organelle recycling, and the gold standard of ultrastructural evidence for autophagy of double-membrane autophagosomes and mitophagosomes were evident from 32 WG, followed by basal infoldings of RPE cell membrane at 36 WG. Lipofuscin formation and deposition into the BES evident at six years increased at 17 years. We provide compelling ultrastructural evidence that heterophagy and autophagy begins in the third trimester of human fetal development and that deposition of cellular byproducts into the extracellular space of RPE takes place via exocytosis. Transplanted RPE cells must also demonstrate the capacity to subserve autophagic and heterophagic functions for effective disease mitigation.

An update on the evolutionary origin of aglomerular kidney with structural and ultrastructural descriptions of the kidney in three fish species.

The kidney of fish contains numerous nephrons, each of which is divided into the renal corpuscle and renal tubules. This glomerular structure is the filtration unit of the nephron and is important for the kidney function, but it has been reported that the renal corpuscle was lost in at least four independent linages of fish (i.e., aglomerular kidney). In this study, the authors newly described renal structures for three species by histological and ultrastructural observations: two aglomerular kidneys from a seahorse Hippocampus barbouri and a toadfish Allenbatrachus grunniens and a glomerular kidney from a snake eel Pisodonophis boro. The renal development of H. barbouri was also described during 1-35 days after birth. In all species tested, the anterior kidney was comprised of haematopoietic tissues and a few renal tubules, whereas the posterior kidney contained more renal tubules. Although the glomerular structure was present in P. boro, light microscopic observations identified no glomeruli in the kidney of H. barbouri and A. grunniens. Ultrastructurally, abundant deep basal infoldings with mitochondria in the renal tubules were observed in A. grunniens compared to H. barbouri and P. boro, suggesting the possible role of basal infoldings in maintaining the osmotic balance. By integrating the results from the three species and comprehensive literature search, the authors further showed that 56 species have been reported to be aglomerular, and that the aglomerular kidney has evolved at least eight times in bony fishes.

Therapeutic role of Azadirachta indica leaves ethanolic extract against diabetic nephropathy in rats neonatally induced by streptozotocin

ABSTRACT Diabetic nephropathy (DN) is manifested by chronic loss of renal function due to damage of glomeruli and renal tubules. Therefore, this study is mainly designed to evaluate the therapeutic role of Azadiracta indica (neem) leaves extract as a novel approach for treatment of DN in rats neonatally induced by streptozotocin (STZ). For this study, 40 offspring were selected after parturition and categorized into four groups (n = 10). Group1: control group, group 2: neem leaves extract supplemented group, group 3: diabetic group that injected with a single dose of STZ and group 4: diabetic group treated with neem extract. The results revealed deleterious histological and ultrstructural changes in the renal tissues of diabetic rats. Such changes included atrophied glomeruli, dilated renal cortical tubules and scattered hemorrhage spots, thickening of glomerular basement membrane, expansion of mesangial matrix and pyknotic podocyte. Additionally, the proximal convoluted tubule and distal tubule showed cytoplasmic vacuolation, vacuolated mitochondria, scattered lipid droplets, lost microvilli and disrupted basal lamina and basal infoldings. Moreover, significant decreased levels of serum antioxidants (SOD&CAT) and significant increased levels of serum MDA, urea and creatinine were noticed in diabetic rats. Neem leaves extract successfully alleviated the histological and ultrastructural as well as biochemical changes induced by diabetes.

Tissue-Specific Gamma-Flicker Light Noninvasively Ameliorates Retinal Aging.

Aging is a risk factor for multiple retinal degeneration diseases. Entraining brain gamma oscillations with gamma-flicker light (γFL) has been confirmed to coordinate pathological changes in several Alzheimer's disease mouse models and aged mice. However, the direct effect of γFL on retinal aging remains unknown. We assessed retinal senescence-associated beta-galactosidase (β-gal) and autofluorescence in 20-month-old mice and found reduced β-gal-positive cells in the inner retina and diminished lipofuscin accumulation around retinal vessels after 6 days of γFL. In immunofluorescence, γFL was further demonstrated to ameliorate aging-related retinal changes, including a decline in microtubule-associated protein 1 light chain 3 beta expression, an increase in complement C3 activity, and an imbalance between the anti-oxidant factor catalase and pro-oxidant factor carboxymethyl lysine. Moreover, we found that γFL can increase the expression of activating transcription factor 4 (ATF4) in the inner retina, while revealing a decrease of ATF4 expression in the inner retina and positive expression in the outer segment of photoreceptor and RPE layer for aged mice. Western blotting was then used to confirm the immunofluorescence results. After mRNA sequencing (NCBI Sequence Read Archive database: PRJNA748184), we found several main mechanistic clues, including mitochondrial function and chaperone-mediated protein folding. Furthermore, we extended γFL to aged Apoe-/- mice and showed that 1-m γFL treatment even improved the structures of retinal-pigment-epithelium basal infolding and Bruch's membrane. Overall, γFL can orchestrate various pathological characteristics of retinal aging in mice and might be a noninvasive, convenient, and tissue-specific therapeutic strategy for retinal aging.

Ultrastructural identification of developing proximal tubules based on three-dimensional reconstruction.

BackgroundThe cellular mechanisms involved in the development of proximal tubules are not only associated with morphogenesis in fetal life, but also with restoration of damaged tubules in adulthood. Knowledge about morphological features of cell differentiation and proliferation along the developing tubule is insufficient, which hinders identification of the cellular origin.ObjectivesThis study aimed to investigate ultrastructures of the proximal tubule at different stages of nephrogenesis.MethodsElectron microscopy was used and guided by computer‐assisted tubular tracing to identify the cellular structures.ResultsRenal vesicles and S‐shaped bodies revealed more proliferative features, such as densely‐packed fusiform‐shaped cells with numerous protein‐producing organelles than membrane specializations typical for mature tubules. At the capillary‐loop stage the proximal tubules demonstrated all characteristics of the mature tubules, but not as developed, including shorter but densely packed microvilli, fewer lateral processes with cell‐cell contacts, lower basal membrane infoldings, and lower mitochondrial volume density. However, they exhibited an elaborated endocytic system above the nucleus, indicating a membrane transport is being established. Abundant free‐ and endoplasmic reticulum‐adhered ribosomes and Golgi complexes reflected active protein synthesis for cell growth and proliferation. Interestingly, electron dense cells were occasionally intermixed with electron lucent cells characterized by various organelles in less cytosol and a larger nucleus with abundant euchromatin, which is a feature of active proliferation.ConclusionsThese ultrastructures indicate that the morphogenesis of the developing proximal tubule corresponds to the gradually established physiological activities. The two different cellular electron densities may suggest distinctive differentiation of the cells along the tubule.

Impact of Remdesivir on the kidney and potential protective capacity of Granulocyte-Colony Stimulating Factor versus Bone Marrow Mesenchymal Stem Cells in adult male albino rats

Background: Remdesivir is a novel broad spectrum antiviral drug previously used to treat Ebola. It is a pro-drug nucleoside with antiviral activity that is opposed to SARS-CoV-2 and coronavirus. Aim: Current research was planned to evaluate and compare the potential ameliorative impact of the hematopoietic-stem-cell mobilized by the granulocyte colony-stimulating factor (G-CSF) versus BM-MSC on the effect of novel antiviral remdesivir on the kidney.Materials and methods: Rats divided into four groups: control group, Remdesivir treated group (20 mg/kg/day IV on the first day followed by 10 mg/kg/day for 6 days), Remdesivir + BM-MSCs group (3x10⁶ cells/ml of PKH26 labelled MSC) and Remedesivir+ Filgrastim group (70 μg/kg/day/5 days). At the end of the experiment, animals were anaesthetized and sacrificed. Both animal kidneys were excised for histological, immunohistochemistry, and electron microscopy studies. Biochemical and morphometric assessments had been performed.Results: Remdesivir caused distortion and degeneration of both the glomeruli and the renal tubules associated with Bowman’s space widening. It greatly increased the deposition of collagen and enhanced the expression of caspase 3, IL-6, and TGF-β1. Ultrastructure changes were observed in the form of thickening of glomerular basement membrane, dilated basal plasma membrane infoldings of tubular epithelium and mitochondrial degeneration. Biochemically, decreased antioxidant enzymes, reduced glutathione (GSH), superoxide dismutase (SOD), and catalase (CAT) with increased serum urea and creatinine were also recorded. Both BM-MSCs and G-CSF improved histological structure and function of the kidney. Conclusion: Prescribing drugs such as remdesivir should be carried out with severe care. BM-MSCs and G-CSF are an efficient and ideal option to protect patients from irreversible kidney damage.

Choroidal and Retinal Changes After Systemic Adrenaline and Photodynamic Therapy in Non-Human Primates.

PurposeTo determine the tomographic, angiographic, and histologic changes in the choroid and retina of cynomolgus monkeys after systemic adrenaline and verteporfin photodynamic therapy (vPDT).MethodsSix cynomolgus monkeys (12 eyes) were treated with vPDT only (n = 2), adrenaline only for eight weeks (n = 2), adrenaline for eight weeks with vPDT at week 4 (n = 4), and adrenaline for 12 weeks and vPDT at week 8 (n = 4). Spectral-domain optical coherence tomography, angiography, and autofluorescence were performed at baseline and every 14 days thereafter until 28 days after adrenaline therapy or vPDT. Choroid parameters included choroidal thickness (CT) changes and structural changes using semiautomated image binarization. Histology with light and electron microscopy was performed.ResultsAdrenaline resulted in subfoveal CT increase at week 4 compared with baseline (3.4%, P = 0.010), with further increase at week 8 (3.9%, P = 0.007). This correlated with choroidal luminal area increase (16.0% at week 8 compared with baseline, P = 0.030). Outer retinal changes included subretinal fluid, ellipsoid zone (EZ) disruption, photoreceptor elongation, and sub/intraretinal bright dots. Hypocyanescent spots surrounded by leakage was observed. Histology showed dilated choroidal vessels, intracytoplasmic vacuoles, and retinal pigment epithelium (RPE) enlarged basal infoldings. The vPDT decreased subfoveal CT at four weeks after vPDT (−7.5%, P = 0.007). This correlated with choroidal stromal area decrease (−18.0%, P < 0.010). Within the treatment spot, there was outer retinal atrophy, EZ disruption, irregular RPE thickening, intense hypoautofluorescence, hyperfluorescence, and hypocyanescence. On histology, there were outer retina, RPE, and choroid changes.ConclusionsAdrenaline induces choroidal vessel dilation and CT increase. The vPDT decreases CT because of a reduction in choroidal stromal component.

Transmission Electron Microscopy as a Tool to Study the Toxicological Effects of Thiamethoxam in Workers of Atta sexdens (Myrmicinae, Attini).

Thiamethoxam is a neonicotinoid that has been used to control insect pests. The literature reports a few behavioral studies evaluating the toxic effect of thiamethoxam in ants; however, there are scarce studies at the cellular level. The present research evaluated the effects of thiamethoxam in labial (LG) and mandibular glands (MG), fat bodies (FB), and Malpighian tubules (MT) of workers of Atta sexdens, using transmission electron microscopy. The duct and secretory cells of LG were profoundly affected, then the production of saliva can be compromised, as well as its quality and subsequent use. In MG, reservoir and canaliculi cells presented slight alterations; however, MG secretory cells presented vacuoles containing lamellar structures, increased lipid production, and a large amount of mitochondria, which may lead to organ's malfunctioning. The FB cell alterations do not seem enough to cause significant changes that lead to cell death. Prominent changes in MT, such as loss of the electron-dense concentric ring, increased smooth endoplasmic reticulum, loss of basal infolds, vacuoles containing mineralized granules, and lamellar structures associated with mitochondria, suggest that their excretory function is compromised. In conclusion, thiamethoxam acts not only in the nervous system but also contributes to systemic toxicity on the target organism.

A Multi-Omics Approach Identifies Key Regulatory Pathways Induced by Long-Term Zinc Supplementation in Human Primary Retinal Pigment Epithelium.

In age-related macular degeneration (AMD), both systemic and local zinc levels decline. Elevation of zinc in clinical studies delayed the progression to end-stage AMD. However, the molecular pathways underpinning this beneficial effect are not yet identified. In this study, we used differentiated primary human fetal retinal pigment epithelium (RPE) cultures and long-term zinc supplementation to carry out a combined transcriptome, proteome and secretome analysis from three genetically different human donors. After combining significant differences, we identified the complex molecular networks using Database for Annotation, Visualization and Integrated Discovery (DAVID) and Ingenuity Pathway Analysis (IPA). The cell cultures from the three donors showed extensive pigmentation, development of microvilli and basal infoldings and responded to zinc supplementation with an increase in transepithelial electrical resistance (TEER) (apical supplementation: 443.2 ± 79.3%, basal supplementation: 424.9 ± 116.8%, compared to control: 317.5 ± 98.2%). Significant changes were observed in the expression of 1044 genes, 151 cellular proteins and 124 secreted proteins. Gene set enrichment analysis revealed changes in specific molecular pathways related to cell adhesion/polarity, extracellular matrix organization, protein processing/transport, and oxidative stress response by zinc and identified a key upstream regulator effect similar to that of TGFB1.

Morphological Changes and Potential Mechanisms of Intraocular Pressure Reduction after Micropulse Transscleral Cyclophotocoagulation in Rabbits

Introduction: Micropulse transscleral cyclophotocoagulation (MP-TSCPC) is a method for intraocular pressure (IOP) reduction in patients with glaucoma; however, the specific mechanisms underlying its ability to reduce IOP remain unclear. We therefore investigated the morphological changes and mechanisms of IOP reduction after MP-TSCPC. Methods: The right eyes of 4 pigmented rabbits were treated with MP-TSCPC with power setting corresponding to those used in glaucoma patients (1 power: 2,000 mW; time: 160 s; duty cycle: 31.3%). Power settings of 1, 1/8, 1/16, and 1/32 power were applied to the right eyes. The left eyes were used as controls. A light microscope and electron microscope were used to observe morphological findings after 1 week of MP-TSCPC. IOP and IOP reduction rate were compared before and after MP-TSCPC application on days 1, 3, and 5, and at 1 week. Results: In the pre-MP-TSCPC, IOP was 16.7 ± 0.6 mm Hg. The IOP of rabbit treated with the 1 power was 3 mm Hg, with an IOP reduction rate of 80%; however, the eyes developed phthisis bulbi. The IOP was 7.0 ± 0.0 mm Hg 1 week after MP-TSCPC (IOP reduction rate: 59%) in rabbit treated with the 1/8 power. Reduction in IOP was observed, but there was significant tissue invasion to the ciliary body. The IOP was 10.3 ± 0.6 mm Hg (IOP reduction rate: 40%) 1 week after MP-TSCPC in rabbit treated with the 1/16 power, which was more effective to reduce IOP than that with the 1/8 power. Tissue invasion to the ciliary body was negligible, nonpigmented epithelial cells of the pars plicata were damaged, basal infoldings were destroyed, and repair was accompanied by proliferating tissue. No IOP reduction or tissue change was observed in rabbit treated with the 1/32 power. Conclusion: A potential mechanism for IOP reduction in pigmented rabbits is aqueous humor transport dysfunction due to damage to the nonpigmented epithelial cells of the pars plicata and destruction of basal infoldings. The power of MP-TSCPC was consistent with both morphological changes and IOP reduction.

Yap1 is required for maintenance of adult RPE differentiation.

Nuclear YAP1 plays a critical role in regulation of stem cell proliferation, tissue regeneration, and organ size in many types of epithelia. Due to rapid turnover of most epithelial cell types, the cytoplasmic function of YAP1 in epithelial cells has not been well studied. The retinal pigment epithelium (RPE) is a highly polarized epithelial cell type maintained at a senescence state, and offers an ideal cell model to study the active role of YAP1 in maintenance of the adult epithelial phenotype. Here, we show that the cytoplasmic function of YAP1 is essential to maintain adult RPE differentiation. Knockout of Yap1 in the adult mouse RPE caused cell depolarization and tight junction breakdown, and led to inhibition of RPE65 expression, diminishment of RPE pigments, and retraction of microvilli and basal infoldings. These changes in RPE further prompted the loss of adjacent photoreceptor outer segments and photoreceptor death, which eventually led to decline of visual function in older mice between 6 and 12months of age. Furthermore, nuclear β-catenin and its activity were significantly increased in mutant RPE. These results suggest that YAP1 plays an important role in active inhibition of Wnt/β-catenin signaling, and is essential for downregulation of β-catenin nuclear activity and prevention of dedifferentiation of adult RPE.

Ultrastructure of the prosomal gland complex in unfed larvae of the fresh-water mite Limnesia maculata (Müller, 1776) (Acariformes, Limnesiidae)

The salivary and coxal glands in unfed larvae of the fresh-water mite Limnesia maculata (Müller, 1776) (Acariformes, Limnesiidae) were studied using light and electron microscopy. Three pairs of the salivary and one pair of the coxal glands constitute the prosomal gland complex. The salivary glands pertain to simple alveolar glands consisting of the single acinus with prismatic cells arranged around the intra-alveolar lumen. Owing to their spatial distribution, the salivary glands may be termed as medial, ventral and lateral. While the ventral and lateral glands are arranged symmetrically, the medial glands are disposed one after another at the frontal wall of the synganglion (brain). The medial and the ventral glands possess mostly electron-dense secretory granules supposedly of protein nature. The lateral glands show variable organization mainly having electron-lucent vacuoles. No well pronounced rough endoplasmic reticulum and Golgi bodies were discernible in the salivary glands. The coxal glands are well developed and composed of (i) the main portion (the so-called labyrinth) including at least two tightly opposed loops and extending backward along the brain, and (ii) the very short anterior portion/end piece transforming anteriorly into the terminal sac/bladder. The cells of the main portion are provided with apical microvilli, whereas the basal infolding/basal labyrinth is lacking. The cells of the anterior portion do not show the apical microvilli and the basal infoldings. The terminal sac is lined by a cuticle and has an ectodermal origin. The ducts of the salivary glands come together at the dorsal aspect of the bladder, to which they open forming the common podocephalic duct anteriorly. The latter opens on each side into the subcheliceral space. The well-developed podocephalic system suggests its active role in the living processes such as feeding and ion-water balance.

Circular Noncoding RNA NR3C1 Acts as a miR-382-5p Sponge to Protect RPE Functions via Regulating PTEN/AKT/mTOR Signaling Pathway

Age-related macular degeneration (AMD) is a universal leading cause for irreversible blindness in the elderly population. Dedifferentiation of retinal pigment epithelium (RPE) cells initiates early pathological events in atrophic AMD. Herein, we aim to investigate effects of a circular RNA derived from the NR3C1 gene (circNR3C1) on regulating RPE function and AMD pathogenesis. circNR3C1 expression was consistently upregulated along with RPE differentiation and was downregulated in dysfunctional RPE and blood serum of AMD patients. Silencing of circNR3C1 reduced RPE characteristic transcripts and proteins, interrupted phagocytosis, accelerated intracellular reactive oxygen species (ROS) generation, and promoted RPE proliferation invitro. circN3C1 silencing also decreased expressions of RPE characteristic markers and disturbed the ultrastructure of RPE invivo, as shown by a thickened RPE with twisted basal infoldings and outer segments. Mechanistically, circNR3C1 acted as an endogenous microRNA-382-5p (miR-382-5p) sponge to sequester its activity, which increased phosphatase and tensin homolog on chromosome 10 (PTEN) expression and inhibited the protein kinase B/mammalian target of rapamycin (AKT/mTOR) pathway. miR-382-5p overexpression and PTEN silencing mimicked effects of circNR3C1 silencing on RPE phenotypes invivo and invitro. In conclusion, circNR3C1 prevents AMD progression and protects RPE by directly sponging miR-382-5p to block its interaction with PTEN and subsequently blocks the AKT/mTOR pathway. Pharmacological circNR3C1 supplementations are promising therapeutic options for atrophic AMD.

Specialized stellate cells offer a privileged route for rapid water flux in Drosophila renal tubule

Insects are highly successful, in part through an excellent ability to osmoregulate. The renal (Malpighian) tubules can secrete fluid faster on a per-cell basis than any other epithelium, but the route for these remarkable water fluxes has not been established. In Drosophila melanogaster, we show that 4 genes of the major intrinsic protein family are expressed at a very high level in the fly renal tissue: the aquaporins (AQPs) Drip and Prip and the aquaglyceroporins Eglp2 and Eglp4 As predicted from their structure, and by their transport function by expressing these proteins in Xenopus oocytes, Drip, Prip, and Eglp2 show significant and specific water permeability, whereas Eglp2 and Eglp4 show very high permeability to glycerol and urea. Knockdowns of any of these genes result in impaired hormone-induced fluid secretion. The Drosophila tubule has 2 main secretory cell types: active cation-transporting principal cells, wherein the aquaglyceroporins localize to opposite plasma membranes, and small stellate cells, the site of the chloride shunt conductance, with these AQPs localizing to opposite plasma membranes. This suggests a model in which osmotically obliged water flows through the stellate cells. Consistent with this model, fluorescently labeled dextran, an in vivo marker of membrane water permeability, is trapped in the basal infoldings of the stellate cells after kinin diuretic peptide stimulation, confirming that these cells provide the major route for transepithelial water flux. The spatial segregation of these components of epithelial water transport may help to explain the unique success of the higher insects in regulating their internal environments.

NEPHROTOXICITY OF 5-FLUOROURACIL IN MALE MICE AND THE PROBABLE PROTECTIVE ROLE OF VITAMIN C: HISTOLOGICAL AND ULTRASTRUCTURAL STUDIES

The present study investigated the probable protective role of vitamin C in alleviating 5-fluorouracil (5-Fu)-induced nephrotoxicity in male mice (Mus musculus). Thirty male CD-1 mice were equally divided into three groups: Group I (the control group), received 0.9% NaCl; group II, received intraperitoneally (i.p.) 80 mg of 5-Fu/kg body weight (b.wt)/day for four weeks; group III, received (i.p.) 80 mg of 5-Fu plus 12 mg of vitamin C/kg b.wt/day for four weeks. Animals of all groups were killed at the end of the experiment, and the renal tissue samples were taken and processed for light and electron microscopical examinations. Light microscopic observations revealed that administration of 5-Fu caused erosion of the parietal cells of Bowman's capsules, widening of the urinary spaces, and disruption of the glomerular capillaries and hemorrhage. The cells of the proximal and distal tubules exhibited vacuolar degeneration and coagulative necrosis. The nuclei of these cells manifested pyknosis and karyolysis. Ultrastructural examination revealed damage of the parietal epithelium of Bowman's capsules with fusion and destruction of the foot processes of the podocytes. The cells of the proximal tubules displayed destruction of the microvilli constituting the brush borders and degeneration of the mitochondria. The distal tubules displayed destruction of both the basal infoldings and the mitochondria with fragmentation of the rough endoplasmic reticulum. Histological and ultrastructural results revealed that the treatment with vitamin C simultaneously with 5-Fu led to apparent protection of the renal tissue. This might suggest that vitamin C has a protective potential against 5-Fu-induced nephrotoxicity.

Histochemical and ultrastructural investigations on the renal parenchyma of the Egyptian Nile Monitor Lizard (Varanus niloticus)

AbstractVaranus niloticus (Linnaeus, 1766), the Nile monitor lizard, is considered the largest lizard in Africa and one of the most widespread. The Egyptian Nile monitor lizard exists in variable habitats, from grasslands to rainforests. This study pointed to investigate the light and ultrastructural features of the renal tissue of this lizard. Microscopically, the lizard nephron deprived from loop of henle and no demarcation could be detected between the cortical and medullary tissues. The renal corpuscles were small, but complex structures. The proximal convoluted tubules were lined by acidophilic cuboidal cells with hemosiderin pigment in their apical cytoplasm. The cytoplasm of the distal convoluted tubular cells reacted strongly with alcian blue stain. The sexual segment of the lizard kidney was lined with high columnar cells with massive periodic acid–Schiff‐positive/alcian blue‐negative supra‐nuclear granules. Ultrastructurally, the basal infoldings of the proximal convoluted cells were evident. Supra‐nuclear electron‐dense vesicles were detected in the cytoplasm of the sexual segment cells. In summary, the kidney of the Egyptian Nile monitor lizard shares many histochemical features with other reptiles. However, they own several structural specializations in order to adapt to their harsh environments. Future studies focusing on the histochemical components of the sexual segment secretion would be required.

Remodeling of the Basal Labyrinth of Retinal Pigment Epithelial Cells With Osmotic Challenge, Age, and Disease.

PurposeThe basal surface of the retinal pigment epithelium (RPE) is folded into a complex basal labyrinth thought to facilitate solute and water transport. We aimed to analyze and define the structural organization of the basal labyrinth of the RPE to enable quantitative analysis of structural changes in age and disease and to better understand the relationship between basal labyrinth structure and efficiency of transepithelial transport.MethodsConventional transmission and serial block-face scanning electron microscopy and electron tomography were used to examine the structure of the basal labyrinth in mouse eyes of different ages and genotypes and with and without osmotic shock before fixation.ResultsWe identified structurally distinct zones (stacked and ribbon-like) within the RPE basal labyrinth that are largely organelle free and cisternal elements that make contact with the endoplasmic reticulum (ER) and mitochondria. These zones are lost in a hierarchic fashion with age and prematurely in a model of the progressive retinal degenerative disease, choroideremia. Junctional complexes crosslink closely opposed infoldings. Spacing between the basal infoldings was affected by subtle osmotic changes while osmotic shock induced dramatic remodeling of the infoldings.ConclusionsThe basal labyrinth has complex but ordered structural elements that break down with age and in choroideremia. The geometry of these elements and site of contact with ER and mitochondria likely facilitate the ion transport that drives water transport across the basal RPE surface. Changes in structure in response to local osmotic variation may allow transport to be modulated in order to maintain RPE volume.

Aging changes in the retina of male albino rat: a histological, ultrastructural and immunohistochemical study.

Degenerative changes caused by aging may affect the eye, especially the retina. Such changes occur as a part of normal physiological process and may be irreversible. The aim of the study was to demonstrate the influence of aging on the morphology of the retina to provide a basis to explain the pathogenesis of age-associated decline in visual acuity, scotopic and photopic sensitivity. Forty male albino rats were used and divided into four age groups (group I: age of cortical maturity, group II: middle-aged, group III: aged group and group IV: senile group). The rats were sacrificed, the eye balls were enucleated. Intra-vitreal injections of formalin for haematoxylin and eosin and immunohistochemical sections, glutaraldehyde for toluidine blue semithin and E/M ultra-thin sections were performed. Measurements and quantitative histomorphometric estimation of the layers of the retina were done. Light microscopic examination revealed age-dependent attenuation of photoreceptor striations. Aged and senile groups presented pyknotic, widely- -spaced nuclei of the outer nuclear layer. The inner nuclear layer was thinned out to 2 or 3 cellular rows. Retinal capillaries showed progressive dilatation and congestion. Statistical analysis proved significant thinning of the retina with variable degrees of thinning of the constituting layers. Decreased arborisation with age was confirmed with quantification of synaptophysin-immunostained sections. Glial fibrillary acidic protein immunostaining revealed the picture of reactive gliosis. On the ultrastructural level, the retinal pigment epithelium exhibited major alterations with aging. Numerous phagosomes, lipofuscin and melanolipofusin granules appeared within the cells, together with exaggerated basal infoldings. The pho- toreceptor nuclei became degenerated and the perinuclear space was widened. Rat retinae clearly undergo age-related morphological changes. Such changes provide a cellular base for explanation of decreased vision in humans with aging other than reflection errors. Effect of aging was not only qualitative, but also quantitative.

Ultrastructural differentiation of plasma membrane and cell junctions in the hindgut cells is synchronized with key developmental transitions in Porcellio scaber

Differentiation of transporting epithelial cells during development of animal organisms includes remodelling of apical and basal plasma membranes to increase the available surface for transport and formation of occluding junctions, which maintain a paracellular diffusion barrier. This study provides a detailed ultrastructural analysis of apical and basal plasma membrane remodelling and cell junction formation in hindgut cells during late embryonic and early postembryonic development of the crustacean Porcellio scaber. Hindgut cells in late-stage embryos are columnar with flat apical and basal plasma membranes. In early-stage marsupial mancae the hindgut cells begin to acquire their characteristic dome shape, the first apical membrane folding is evident and the septate junctions expand considerably, all changes being probably associated with the onset of active feeding. In postmarsupial mancae the apical labyrinth is further elaborated and the septate junctions are expanded. This coincides with the transition to an external environment and food sources. First basal infoldings appear in the anterior chamber of early-stage marsupial mancae, but in the papillate region they are mostly formed in postmarsupial mancae. In molting late-stage marsupial mancae, the plasma membrane acquires a topology characteristic of cuticle-producing arthropod epithelia and the septate junctions are considerably reduced.