The IgLON protein Lachesin is required for the blood-brain barrier in Drosophila

In the mammalian peripheral nervous system, nerve insulation depends on the integrity of paranodal junctions between axons and their ensheathing glia. Ultrastructurally, these junctions are similar to the septate junctions (SJ) of invertebrates. In Drosophila, SJ are found in epithelia and in the glia that form the blood-brain barrier (BBB). Drosophila NeurexinIV and Gliotactin, two components of SJ, play an important role in nerve ensheathment and insulation. Here, we report that Drosophila Lachesin (Lac), another SJ component, is also required for a functional BBB. In the developing nervous system, Lac is expressed in a dynamic pattern by surface glia and a subset of neurons. Ultrastructural analysis of Lac mutant embryos shows poorly developed SJ in surface glia and epithelia where Lac is expressed. Mutant embryos undergo a phase of hyperactivity, with unpatterned muscle contractions, and subsequently become paralyzed and fail to hatch. We propose that this phenotype reflects a failure in BBB function.

Cytoplasmic channels and their association with plastids in male meiocytes of tobacco, onion and lily

The ultrastructures of male meiocytes in tobacco, onion and lily were studied to elucidate the interaction between cytoplasmic channels (CCs) and plastids. Before meiosis, the male sporogenous cells had identically thickened cell walls (CWs) traversed by typical plasmodesmata (PDs). After entering meiosis, their CWs became uneven in thickness and 80-500nm aperture CCs were formed. Simultaneously, plastids or plastid-like bodies (PLBs) differing in size and morphology assembled at one or both ends of the CCs. These plastids and PLBs commonly orientated their sharper ends to face the CCs and were co-orientated on the axial line crossing the CC. Such pairs of plastids were often interconnected through the CC by thin (50-100nm) threads emanating from their membranes. Sometimes, plastids or PLBs extended directly from one side of a CW to the other, forming a bridge via the CC. In some cases, several plastids formed bridges between cells via one common CC. This is the first report that clearly demonstrates an intercellular continuum of, or communication between, plastids in male plant meiocytes.

Pigmented Eccrine Poroma Occurring on the Scalp

We describe a man with a pigmented poroma on the scalp mimicking a pigmented melanocytic nevus. Histopathological examination showed that melanocytes were mostly distributed at the periphery of the tumor masses. It is suggested that melanocytes in the tumor masses may have migrated from the adjacent epidermis.

Claudins in occluding junctions of humans and flies

The epithelial barrier is fundamental to the physiology of most metazoan organ systems. Occluding junctions, including vertebrate tight junctions and invertebrate septate junctions, contribute to the epithelial barrier function by restricting free diffusion of solutes through the paracellular route. The recent identification and characterization of claudins, which are tight junction-associated adhesion molecules, gives insight into the molecular architecture of tight junctions and their barrier-forming mechanism in vertebrates. Mice lacking the expression of various claudins, and human hereditary diseases with claudin mutations, have revealed that the claudin-based barrier function of tight junctions is indispensable in vivo. Interestingly, claudin-like molecules have recently been identified in septate junctions of Drosophila. Here, we present an overview of recent progress in claudin studies conducted in mammals and flies.

Ultrastructural aspects of the intercellular bridges between female bee germ cells

The germline cells in the ovary of the female bee are interconnected by intercellular bridges kept open by cytoskeletal reinforcements in the plasmic membrane. These bridges among the germline cells display a dynamic behavior and probably act in the determination of the oocyte among the cells of the clone formed by the premeiotic mitoses, subsequently forming a pathway that enables the products synthesized by the nurse cells to reach the oocyte during its maturation. The cytoskeletal elements in the intercellular bridges of bee gonads are basically microfilaments and microtubules, but another type of filament (thick, of non-defined nature, associated with elements of the endoplasmic reticulum) is present in the bridges between the premeiotic cystocytes. This filament crosses the bridge, using microfilaments to fasten itself to the plasmic membrane. These filaments appear to control the span of the bridge. Upon completion of the proliferation phase the cystocytes take on a rosette shape, and a fusome formed by the convergence of the bridges appears at their center. The thick filaments are not present in this conformation. The differentiation of the oocyte and the nurse cells leads to a new change, in which the bridges are reoriented to convey the content of the future nurse cells to the oocyte.

Developmental control of nuclear morphogenesis and anchoring by charleston, identified in a functional genomic screen of Drosophila cellularisation

Morphogenesis of epithelial tissues relies on the precise developmental control of cell polarity and architecture. In the early Drosophila embryo, the primary epithelium forms during cellularisation, following a tightly controlled genetic programme where specific sets of genes are upregulated. Some of them, for example, control membrane invagination between the nuclei anchored at the apical surface of the syncytium. We used microarrays to describe the global programme of gene expression underlying cellularisation and identified distinct classes of upregulated genes during this process. Fifty-seven genes were then tested functionally by RNAi. We found six genes affecting various aspects of cellular architecture: membrane growth, organelle transport or organisation and junction assembly. We focus here on charleston (char), a new regulator of nuclear morphogenesis and of apical nuclear anchoring. In char-depleted embryos, the nuclei fail to maintain their elongated shape and, instead, become rounded. In addition, together with a disruption of the centrosome-nuclear envelope interaction, the nuclei lose their regular apical anchoring. These nuclear defects perturb the regular columnar organisation of epithelial cells in the embryo. Although microtubules are required for both nuclear morphogenesis and anchoring, char does not control microtubule organisation and association to the nuclear envelope. We show that Char is lipid anchored at the nuclear envelope by a farnesylation group, and localises at the inner nuclear membrane together with Lamin. Our data suggest that Char forms a scaffold that regulates nuclear architecture to constrain nuclei in tight columnar epithelial cells. The upregulation of Char during cellularisation and gastrulation reveals the existence of an as yet unknown developmental control of nuclear morphology and anchoring in embryonic epithelia.

Group BStreptococcusCrosses Human Epithelial Cells by a Paracellular Route

Colonization of the colon and vagina is thought to be important in the pathogenesis of group B Streptococcus (GBS) infection. However, little is known about the strategies used by GBS to translocate through the epithelial barrier during the onset of disease. We used differentiated epithelial cells grown on transwell inserts as a model of the epithelial barrier. Bacterial translocation occurred without a detectable decrease in transepithelial resistance. Whereas acapsular GBS was better able to adhere to and invade epithelial cells, the percentage of bacteria translocating across the epithelial monolayer was independent of the presence of the capsule. Transmission electron microscopy showed the intimate association of GBS with intercellular junctions and the capacity to cross the monolayer by a paracellular mechanism. This process consisted of an active and transient opening of cell junctions. Indeed, GBS was preferentially found along the cell perimeter, where it colocalized with junctional protein complexes.

Morphological and histological study of the ostrich (Struthio Camelus L.) liver and biliary system

The peculiarity of the digestive system of the ostrich (Struthio Camelus L.), which is characterized by the continuous production of bile, led us to undertake macroscopical and histological studies of the liver and its biliary system, since very little bibliographic data exist on the subject. For this purpose we observed the organs of male and female ostriches 16-18 months of age, in situ, in order to describe their location, relationships and morphology. Samples of the liver were processed for observation by light microscopy; samples of the hepatoenteric duct were processed for observation by light and electron microscopy. Our findings regarding the liver revealed the presence of two lobes: a left lobe, subdivided into three lobes, and a right undivided lobe. There was no gall-bladder. The histological picture showed unlimited hepatic lobules, with hepatocytes arranged in cord-like fashion two cells thick. A large hepatoenteric duct arose from the porta hepatis, and opened into a papilla in the descending limb of the duodenum. The mucosa of the duct was lined by simple columnar epithelium consisting of cells having the same morphological cytoplasmatic features but distinguished by either a light or a dark nucleus.

Ultrastructural and immunohistochemical analysis of rat uroepithelial cell junctions after partial bladder outlet obstruction and selective COX-2 inhibitor treatment

The present study was undertaken to evaluate alterations in uroepithelial cell junctional complexes in partial bladder outlet obstruction (PBOO) of rat bladders using ultrastructural morphometry and immunohistochemistry, and to determine whether selective COX-2 inhibitors have any effects on these structures. A total of 18 male rats were separated into three groups of six rats each: (1) sham-operated animals served as controls; (2) a PBOO group, without further treatment (3) and a group that immediately after PBOO, received treatment for 4 weeks with oral Celecoxib, a selective COX-2 inhibitor. Uroepithelial cell junctions were evaluated using transmission electron microscopy combined with morphometry. Results were also assessed by E-cadherin and alpha-catenin immunohistochemistry. Morphometrical analysis of ultrastructural evaluations revealed that 4 weeks of PBOO caused a significant reduction in the electron density of zonula adherens and zonula occludens junctional complexes. Moreover, some desmosomes located between the deeper cells of the uroepithelium showed signs of disintegration. Selective COX-2 inhibitor treatment during 4 weeks of PBOO showed protective effects on adherens and occludens junctions, as well as on desmosomes. Immunohistochemical analysis of E-cadherin confirmed that the decreased E-cadherin immunolabelling in 4 weeks of PBOO was prevented by selective COX-2 inhibitor treatment. Based on ultrastructural morphometrical analysis, we conclude that PBOO alone and in combination with selective COX-2 inhibitors can have considerable effects on uroepithelial cellular junctions. Our findings provide a novel area of investigation regarding the selective use of COX-2 inhibitors following PBOO.

Pemphigus foliaceus IgG causes dissociation of desmoglein 1-containing junctions without blocking desmoglein 1 transinteraction

Autoantibodies against the epidermal desmosomal cadherins desmoglein 1 (Dsg1) and Dsg3 have been shown to cause severe to lethal skin blistering clinically defined as pemphigus foliaceus (PF) and pemphigus vulgaris (PV). It is unknown whether antibody-induced dissociation of keratinocytes is caused by direct inhibition of Dsg1 transinteraction or by secondary cellular responses. Here we show in an in vitro system that IgGs purified from PF patient sera caused cellular dissociation of cultured human keratinocytes as well as significant release of Dsg1-coated microbeads attached to Dsg-containing sites on the keratinocyte cellular surface. However, cell dissociation and bead release induced by PF-IgGs was not caused by direct steric hindrance of Dsg1 transinteraction, as demonstrated by single molecule atomic force measurements and by laser trapping of surface-bound Dsg1-coated microbeads. Rather, our experiments strongly indicate that PF-IgG-mediated dissociation events must involve autoantibody-triggered cellular signaling pathways, resulting in destabilization of Dsg1-based adhesive sites and desmosomes.

Constitutive eNOS-derived nitric oxide is a determinant of endothelial junctional integrity

Basal vascular endothelial permeability is normally kept low in part by the restrictiveness of interendothelial junctions (IEJs). We investigated the possible role of nitric oxide (NO) in controlling IEJ integrity and thereby regulating basal vascular permeability. We determined the permeability of continuous endothelia in multiple murine vascular beds, including lung vasculature, of wild-type mice, endothelial nitric oxide synthase (eNOS) null mice, and mice treated with NOS inhibitor N-nitro-L-arginine methyl ester (L-NAME). Light and electron microscopic studies revealed that L-NAME treatment resulted in IEJs opening within a few minutes with a widespread response within 30 min. We observed a 35% increase in transendothelial transport of albumin, using as tracer dinitrophenylated albumin in mouse lungs and other organs studied. To rule out the involvement of blood cells in the mechanism of increased endothelial permeability, vascular beds were flushed free of blood, treated with L-NAME, and perfused with the tracer. The open IEJs observed in these studies indicated a direct role for NO in preserving the normal structure of endothelial junctions. We also used the electron-opaque tracer lanthanum chloride to assess vascular permeability. Lanthanum chloride was presented by perfusion to various vascular beds of mice lacking NO. Open IEJs were seen only in capillary and venular endothelial segments of mice lacking NO, and there was a concomitant increase in vascular permeability to the tracer. Together, these data demonstrate that constitutive eNOS-derived NO is a crucial determinant of IEJ integrity and thus serves to maintain the low basal permeability of continuous endothelia.

Septate junctions mediate the barrier to paracellular permeability in sea urchin embryos

In sea urchin embryos, blastula formation occurs between the seventh and tenth cleavage and is associated with changes in the permeability properties of the epithelium although the structures responsible for mediating these changes are not known. Tight junctions regulate the barrier to paracellular permeability in chordate epithelia; however, the sea urchin blastula epithelium lacks tight junctions and instead possesses septate junctions. Septate junctions are unique to non-chordate invertebrate cell layers and have a characteristic ladder-like appearance whereby adjacent cells are connected by septa. To determine the function of septate junctions in sea urchin embryos, the permeability characteristics of the embryonic sea urchin epithelia were assessed. First, the developmental stage at which a barrier to paracellular permeability arises was examined and found to be in place after the eighth cleavage division. The mature blastula epithelium is impermeable to macromolecules; however, brief depletion of divalent cations renders the epithelium permeable. The ability of the blastula epithelium to recover from depletion of divalent cations and re-establish a barrier to paracellular permeability using fluorescently labelled lectins was also examined. Finally, septate junction structure was examined in embryos in which the permeability status of the epithelium was known. The results provide evidence that septate junctions mediate the barrier to paracellular permeability in sea urchin embryos.

Endocytosis of the apical junctional complex: mechanisms and possible roles in regulation of epithelial barriers

Tight junctions (TJ) and adherens junctions (AJ) regulate cell-cell adhesion and barrier function of simple polarized epithelia. These junctions are positioned in the apical end of the lateral plasma membrane and form the so-called apical junctional complex (AJC). Although initially seen as purely structural features, the AJC is now known to play important roles in cell differentiation and proliferation. The AJC is a highly dynamic entity, undergoing rapid remodeling during normal epithelial morphogenesis and under pathologic conditions. There is growing evidence that remodeling of the AJC is mediated by internalization of junctional proteins. This review summarizes what is known about endocytic pathways, intracellular destinations and signaling cascades involved in internalization of AJC proteins. Potential biological roles for AJC endocytosis in maintaining functional apical junctions, reversible opening of epithelial barrier and disruption of intercellular adhesion are also discussed.

Novel type of interstitial cell (Cajal-like) in human fallopian tube

We describe here--presumably for the first time--a Cajal-like type of tubal interstitial cells (t-ICC), resembling the archetypal enteric ICC. t-ICC were demonstrated in situ and in vitro on fresh preparations (tissue cryosections and primary cell cultures) using methylene-blue, crystal-violet, Janus-Green B or MitoTracker-Green FM Probe vital stainings. Also, t-ICC were identified in fixed specimens by light microscopy (methylene-blue, Giemsa, trichrome stainings, Gomori silver-impregnation) or transmission electron microscopy (TEM). The positive diagnosis of t-ICC was strengthened by immunohistochemistry (IHC; CD117/c-kit+ and other 14 antigens) and immunofluorescence (IF; CD117/c-kit+ and other 7 antigens). The spatial density of t-ICC (ampullar-segment cryosections) was 100-150 cells/mm2. Non-conventional light microscopy (NCLM) of Epon semithin-sections revealed a network-like distribution of t-ICC in lamina propria and smooth muscle meshwork. t-ICC appeared located beneath of epithelium, in a 10-15 microm thick 'belt', where 18+/-2% of cells were t-ICC. In the whole lamina propria, t-ICC were about 9%, and in muscularis approximately 7%. In toto, t-ICC represent ~8% of subepithelial cells, as counted by NCLM. In vitro, t-ICC were 9.9+/-0.9% of total cell population. TEM showed that the diagnostic 'gold standard' (Huizinga et al., 1997) is fulfilled by 'our' t-ICC. However, we suggest a 'platinum standard', adding a new defining criterion- characteristic cytoplasmic processes (number: 1-5; length: tens of microm; thickness: < or =0.5 microm; aspect: moniliform; branching: dichotomous; organization: network, labyrinthic-system). Quantitatively, the ultrastructural architecture of t-ICC is: nucleus, 23.6+/-3.2% of cell volume, with heterochromatin 49.1+/-3.8%; mitochondria, 4.8+/-1.7%; rough and smooth endoplasmic-reticulum (1.1+/-0.6%, 1.0+/-0.2%, respectively); caveolae, 3.4+/-0.5%. We found more caveolae on the surface of cell processes versus cell body, as confirmed by IF for caveolins. Occasionally, the so-called 'Ca2+-release units' (subplasmalemmal close associations of caveolae+endoplasmic reticulum+mitochondria) were detected in the dilations of cell processes. Electrophysiological single unit recordings of t-ICC in primary cultures indicated sustained spontaneous electrical activity (amplitude of membrane potentials: 57.26+/-6.56 mV). Besides the CD117/c-kit marker, t-ICC expressed variously CD34, caveolins 1&2, alpha-SMA, S-100, vimentin, nestin, desmin, NK-1. t-ICC were negative for: CD68, CD1a, CD62P, NSE, GFAP, chromogranin-A, PGP9.5, but IHC showed the possible existence of (neuro)endocrine cells in tubal interstitium. We call them 'JF cells'. In conclusion, the identification of t-ICC might open the door for understanding some tubal functions, e.g. pace-making/peristaltism, secretion (auto-, juxta- and/or paracrine), regulation of neurotransmission (nitrergic/purinergic) and intercellular signaling, via the very long processes. Furthermore, t-ICC might even be uncommitted bipotential progenitor cells.

Functional Connectivity between Immune Cells Mediated by Tunneling Nanotubules

Intercellular signals can be transmitted through neuronal synapses or through gap junctions, with the latter mediating transmission of calcium fluxes and small molecules between cells. We show here that a third form of communication between cells can be mediated by tunneling nanotubules (TNT). When myeloid-lineage dendritic cells and monocytes are triggered to flux calcium by chemical or mechanical stimulation, the signal can be propagated within seconds to other cells at distances hundreds of microns away via TNT. A complex and transient network of TNT is seen in live cells, with individual tubules exhibiting substantial variation in length and diameter. In addition to calcium fluxes, microinjected dye tracers can be transferred through these connections. Following TNT-mediated stimulation, spreading of lamellipodia occurs in dendritic cells characteristic of that seen during the phagocytic response to bacteria. These results demonstrate that nonneuronal cells can transmit signals to distant cells through a physically connected network.

Dual interaction of JAM-C with JAM-B and alpha(M)beta2 integrin: function in junctional complexes and leukocyte adhesion

The junctional adhesion molecules (JAMs) have been recently described as interendothelial junctional molecules and as integrin ligands. Here we show that JAM-B and JAM-C undergo heterophilic interaction in cell-cell contacts and that JAM-C is recruited and stabilized in junctional complexes by JAM-B. In addition, soluble JAM-B dissociates soluble JAM-C homodimers to form JAM-B/JAM-C heterodimers. This suggests that the affinity of JAM-C monomers to form dimers is higher for JAM-B than for JAM-C. Using antibodies against JAM-C, the formation of JAM-B/JAM-C heterodimers can be abolished. This liberates JAM-C from its vascular binding partner JAM-B and makes it available on the apical side of vessels for interaction with its leukocyte counter-receptor alpha(M)beta2 integrin. We demonstrate that the modulation of JAM-C localization in junctional complexes is a new regulatory mechanism for alpha(M)beta2-dependent adhesion of leukocytes.

Parenthesome structure of some corticioid fungi

The parenthesome structure of seven corticioid species, traditionally referred to the family Corticiaceae (Basidiomycota), were studied in order to better understand their taxonomic position: Phanerochaete velutina, Phlebia radiata, P. rufa, Rhizochaete americana (syn. Ceraceomyces americana), R. brunnea, R. filamentosa (syn. Phanerochaete filamentosa) and R. radicata (syn. Phanerochaete radicata). All possessed the perforate type of parenthesome that is commonly encountered in homobasidiomycetes. This feature excludes the above taxa from both the hymenochaetoid and the cantharelloid clades which are the only groups that have imperforate parenthesomes in the homobasidiomycetes.

Polysialic acid is required for active phases of morphological plasticity of neurosecretory axons and their glia

The morphology of axons and astrocytes in the neurohypophysis changes considerably during physiological stimulation, increasing neurovascular contact and facilitating neurosecretion. We here assessed the contribution of alpha2, 8-linked polysialic acid (PSA), which intervenes in axonal changes during development and covers all neurohypophysial axon and glial surfaces. Using an in vitro model, we first analyzed neurohypophysial ultrastructure under different conditions of plasticity. After 2 h incubation in hyperosmotic medium or with the beta-adrenergic agonist, isoprenaline, neurovascular contact significantly increased, due essentially to an enhanced number of terminals, and gliovascular contact decreased correspondingly. This morphology was maintained during 22 h exposure to isoprenaline and reversed 2 h after agonist washout. Removal of PSA from cell surfaces with endoneurominidase prevented stimulation-related induction and reversal of axon and glial changes but had no effect once remodeling had occurred. PSA, therefore, by promoting dynamic cell interactions, is necessary for plasticity of axons and their associated glia.

The Caenorhabditis elegans aristaless orthologue, alr-1, is required for maintaining the functional and structural integrity of the amphid sensory organs

The homeobox-containing aristaless-related protein ARX has been directly linked to the development of a number of human disorders involving mental retardation and epilepsy and clearly plays a critical role in development of the vertebrate central nervous system. In this work, we investigate the role of ALR-1, the Caenorhabditis elegans aristaless orthologue, in amphid sensory function. Our studies indicate that ALR-1 is required for maintenance of the amphid organ structure throughout larval development. Mutant analysis indicates a progressive loss in the amphid neurons' ability to fill with lipophilic dyes as well as a declining chemotactic response. The degeneration in amphid function corresponds with a failure of the glial-like amphid socket cell to maintain its specific cell shape and cell-cell contacts. Consistent with ALR-1 expression within the amphid socket cell, our results indicate a cell autonomous role for ALR-1 in maintaining cell shape. Furthermore, we demonstrate a role for ALR-1 in the proper morphogenesis of the anterior hypodermis. Genetic interaction tests also suggest that ALR-1 may function cooperatively with the cell adhesion processes in maintaining the amphid sensory organs.

CNS myelin paranodes require Nkx6-2 homeoprotein transcriptional activity for normal structure

Homeodomain proteins play critical roles during development in cell fate determination and proliferation, but few studies have defined gene regulatory networks for this class of transcription factors in differentiated cells. Using a lacZ-knock-in strategy to ablate Nkx6-2, we find that the Nkx6-2 promoter is active embryonically in neuroblasts and postnatally in oligodendrocytes. In addition to neurological deficits, we find widespread ultrastructural abnormalities in CNS white matter and aberrant expression of three genes encoding a paranodal microtubule destabilizing protein, stathmin 1, and the paranodal cell adhesion molecules neurofascin and contactin. The involvement of these downstream proteins in cytoskeletal function and cell adhesion reveals mechanisms whereby Nkx6-2 directly or indirectly regulates axon- glial interactions at myelin paranodes. Nkx6-2 does not appear to be the central regulator of axoglial junction assembly; nonetheless, our data constitute the first evidence of such a regulatory network and provide novel insights into the mechanism and effector molecules that are involved.

Formation and structure of transplantable tissue constructs generated in simulated microgravity from Sertoli cells and neuron precursors

Cell transplantation therapy for Parkinson's disease (PD) has received much attention as a potential treatment protocol for this neurodegenerative condition. Although there have been promising successes with this approach, it remains problematic, especially regarding the inability to provide immediate trophic support to the newly grafted cells and the inability to prevent acute and/or long-term graft rejection by the host. To address these issues of cell graftability, we have created a novel tissue construct from isolated rat Sertoli cells (SC) and the NTerra-2 immortalized human neuron precursor cell line (NT2) utilizing NASA-developed simulated microgravity technology. The two cell types were cocultured at a 1:4 (SC/NT2) ratio in the High Aspect Rotating Vessel (HARV) biochamber for 3 days, after which a disc-shaped aggregate (1-4 mm diameter) was formed. Sertoli neuron aggregated cells (SNAC) were collected by gravity sedimentation and processed either for light and electron microscopy or for fluorescent immunocytochemistry. Intra-SNAC clusters of SC and NT2 cells were identified by anti-human mitochondrial protein (huMT--specific for NT2 cells) and cholera toxin subunit B (CTb--specific for SC). There was little evidence of cell death throughout the aggregate and the absence of central necrosis, as might be expected in such a large aggregate in vitro. Ultrastructurally, SC did not express junctional modifications with NT2 cells nor with adjacent SC as is typical of SC in vivo and, in some protocols, in vitro. NT2 cells, however, showed distinct intercellular junction-like densities with adjacent NT2 cells, often defining canaliculi-like channels between the microvillus borders of the cells. The results show that the use of simulated microgravity coculture provides a culture environment suitable for the formation of a unique and viable Sertoli-NT2 (i.e., SNAC) tissue construct displaying intra-aggregate cellular organization. The structural integration of SC with NT2 cells provides a novel transplantable tissue source, which can be tested to determine if SC will suppress rejection of the grafted NT2 cells and provide for their short- and long-term trophic support in situ in the treatment of experimental PD.

Atypical Angiomyolipoma of Kidney in a Patient With Tuberous Sclerosis: A Case Report With p53 Gene Mutation Analysis

Angiomyolipoma (AML) is the most common benign mesenchymal tumor of the kidney. It belongs to the family of perivascular epithelioid cell tumors and is typically composed of blood vessels, adipose tissue, and smooth muscle– like cells, which are characteristically positive for HMB-45. Results of recent studies suggest that p53 mutation may play an important role in AML progression. Here, we describe a locally destructive renal AML in a patient with tuberous sclerosis. The tumor consisted of mostly epithelioid cells with marked nuclear pleomorphism and frequent mitoses and was positive for HMB-45. The diagnosis of atypical epithelioid AML was made. Codon alteration in the p53 gene was not detected, despite focal p53 immunoreactivity and single nucleotide polymorphism at exon 6. Our finding indicates no definite link between p53 abnormalities and the atypical appearance of AML. To the best of our knowledge, this is the second renal AML case investigated for p53 mutations.

Strength Measurement of the Sertoli-Spermatid Junctional Complex

The Sertoli cell ectoplasmic specialization (ES) is a specialized domain of the calcium-dependent Sertoli cell-spermatid junctional complex. Not only is it associated with the mechanical adhesion of the cells, but it also plays a role in the morphogenesis and differentiation of the developing germ cells. Abnormal or absent Sertoli ESs have been associated with step-8 spermatid sloughing and subsequent oligospermia. With a micropipette pressure transducing system (MPTS) to measure the force needed to detach germ cells from Sertoli cells, this study examined, for the first time, the strength of the junction between Sertoli cells and spermatids and between Sertoli cells and spermatocytes. The mean force needed to detach spermatocytes from Sertoli cells was 5.25 x 10(-7) pN, prestep-8 spermatids from Sertoli cells was 4.73 x 10(-7) pN, step-8 spermatids from Sertoli cells was 8.82 x 10(-7) pN, and spermatids plus EDTA was 2.16 x 10(-7) pN. These data confirm the hypothesis that step-8 spermatids are more firmly attached to Sertoli cells than are spermatocytes and pre-step-8 spermatids and that calcium chelation reduces binding strength between Sertoli cells and spermatids. The MPTS is a useful tool in studying the various molecular models of the Sertoli-germ cell junctional strength and the role of reproductive hormones and enzymes in coupling and uncoupling of germ cells from Sertoli cells.