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1.
Nat Commun ; 8(1): 1434, 2017 11 10.
Artigo em Inglês | MEDLINE | ID: mdl-29127332

RESUMO

Cerebrospinal fluid (CSF) has been commonly accepted to drain through arachnoid projections from the subarachnoid space to the dural venous sinuses. However, a lymphatic component to CSF outflow has long been known. Here, we utilize lymphatic-reporter mice and high-resolution stereomicroscopy to characterize the anatomical routes and dynamics of outflow of CSF. After infusion into a lateral ventricle, tracers spread into the paravascular spaces of the pia mater and cortex of the brain. Tracers also rapidly reach lymph nodes using perineural routes through foramina in the skull. Using noninvasive imaging techniques that can quantify the transport of tracers to the blood and lymph nodes, we find that lymphatic vessels are the major outflow pathway for both large and small molecular tracers in mice. A significant decline in CSF lymphatic outflow is found in aged compared to young mice, suggesting that the lymphatic system may represent a target for age-associated neurological conditions.


Assuntos
Envelhecimento/fisiologia , Líquido Cefalorraquidiano/fisiologia , Vasos Linfáticos/fisiologia , Animais , Aracnoide-Máter/fisiologia , Encéfalo/fisiologia , Corantes/administração & dosagem , Feminino , Sistema Linfático/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos
3.
Brain Res ; 1657: 109-119, 2017 02 15.
Artigo em Inglês | MEDLINE | ID: mdl-27923631

RESUMO

OBJECTIVE: Fibroblast is pervasive in the setting of injury. Its invasion into the arachnoid tissue causes scarring, cortical adhesion of the brain, and obstruction of cerebrospinal fluid outflow. The purpose of this study is to determine the phenotypic and physiologic effects of fibroblasts on arachnoid in culture. METHODS: We studied the effects of fibroblast on the arachnoid cell growth, motility, phenotypic changes, and transport properties. Immortalized rat (Rattus norvegicus, Sprague Dawley breed) arachnoid cells were grown with fibroblast on opposite sides of polyethylene membranes or co-cultured in plastic wells. Arachnoid cell growth rate and DNA content, morphology, transport physiology, and extracellular matriceal content were determined in the presence of normal and irradiated fibroblast cells. RESULTS: When arachnoid cells were grown in the presence of fibroblasts, mannitol permeability increased and transepithelial electrical resistance (TEER) decreased. Arachnoid cell growth rate also significantly decreased. When arachnoid cells were grown in close proximity (i.e. on the same monolayer) with fibroblasts, the arachnoid cells were overrun by day 2, yet when physically separated, no significant change was seen in growth. Apoptosis increased markedly in arachnoid cultures in the presence of fibroblast. Fibroblast caused arachnoid cell to exhibit avoidance behavior, and irradiated fibroblast induced arachnoidal cells to move faster and exhibited greater directional changes. Subcellular glycosaminoglycan (GAG) content was significantly altered by fibroblast. INTERPRETATION: Fibroblasts influence arachnoid cell's mannitol transport likely via soluble factors. While the arachnoid cells did not change morphologically, cell growth was influenced. Over time, the cells had profound changes in transport and motility. The immortalized arachnoid cell/fibroblast culture system provides a unique model mimicking the pathologic event of leptomeningeal scarring.


Assuntos
Aracnoide-Máter/fisiologia , Fibroblastos/fisiologia , Animais , Apoptose/fisiologia , Aracnoide-Máter/citologia , Encéfalo/fisiologia , Encéfalo/efeitos da radiação , Movimento Celular/fisiologia , Técnicas de Cocultura , Colágeno/metabolismo , Impedância Elétrica , Matriz Extracelular/metabolismo , Fibroblastos/efeitos da radiação , Glicosaminoglicanos/metabolismo , Masculino , Manitol , Ratos Sprague-Dawley
4.
Neuroradiology ; 57(2): 139-47, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25398655

RESUMO

INTRODUCTION: Cerebrospinal fluid (CSF) absorption has long been held to predominantly entail drainage into the venous outflow system via the intracranial arachnoid granulations. Newer data suggest pathways involving spinal arachnoid granulations and lymphatic channels may also make substantial contributions to CSF outflow. METHODS: The putative major CSF outflow pathways and their proportionate contribution to CSF absorption were reviewed in this article. RESULTS: CSF is absorbed and drained in bulk not just through cerebral arachnoid granulations (CAG) but also through spinal arachnoid granulations (SAG) and a lymphatic pathway involving egress through cranial and spinal nerve sheaths. The proportions of CSF that efflux through each of these major pathways have yet to be determined with any certainty in humans, though existing evidence (the majority of which is derived from animal studies) suggests that lymphatic pathways may account for up to 50% of CSF outflow-presumably leaving the CAG and SAG to process the balance. CONCLUSION: Knowledge of the CSF pathways holds implications for our ability to understand, prognose, and even treat diseases related to CSF circulation and so is a matter of considerable relevance to neuroradiology and neurology.


Assuntos
Aracnoide-Máter/fisiologia , Encéfalo/fisiologia , Líquido Cefalorraquidiano/fisiologia , Nervos Cranianos/fisiologia , Linfonodos/fisiologia , Medula Espinal/fisiologia , Animais , Humanos , Modelos Biológicos , Reologia/métodos
5.
AJNR Am J Neuroradiol ; 35(9): 1735-9, 2014 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-24948506

RESUMO

BACKGROUND AND PURPOSE: Studies have suggested that arachnoid villi or granulations found in the walls of the cranial dural sinuses, olfactory mucosa, and cranial nerve sheaths function as outlets for intracranial CSF. However, their role as CSF outlets has not yet been verified. Here we show that arachnoid protrusions and contiguous diploic veins provide an alternative drainage route for intracranial CSF. MATERIALS AND METHODS: Four hundred patients with intact skull, dura mater, and dural sinuses underwent MR imaging to explore arachnoids protruding into the skull and diploic veins. Patients with symptoms of increased intracranial pressure or intracranial hypotension were excluded. For 15 patients undergoing craniotomy, both peripheral and diploic venous blood was collected. Albumin and the CSF-specific biomarkers were measured by enzyme-linked immunosorbent assay. RESULTS: With MR imaging, arachnoid protrusions into the skull and contiguous diploic veins were consistently identified throughout the cranium with their characteristic appearance depending on the cranial region. In addition, elevated amounts of prostaglandin D synthase and cystatin C were confirmed in diploic veins compared with peripheral venous blood. CONCLUSIONS: Diploic veins are distributed ubiquitously throughout the cranium. A portion of the intracranial CSF may be drained through arachnoid protrusions and contiguous diploic veins.


Assuntos
Aracnoide-Máter/anatomia & histologia , Aracnoide-Máter/fisiologia , Líquido Cefalorraquidiano/fisiologia , Veias/anatomia & histologia , Veias/fisiologia , Adulto , Idoso , Dura-Máter/irrigação sanguínea , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
6.
Ann Biomed Eng ; 42(4): 812-21, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24322590

RESUMO

The pia-arachnoid complex (PAC) covering the brain plays an important role in the mechanical response of the brain during impact or inertial loading. Recent studies have revealed the complicated material behavior of the PAC. In this study, the nonlinear viscoelastic, transversely isotropic material properties of the PAC were modeled as Mooney-Rivlin ground substance with collagen fibers strengthening within the meningeal plane through an exponential model. The material constants needed were determined using experimental data from in-plane tension, normal traction, and shear tests conducted on bovine specimens. Results from this study provide essential information to properly model the PAC membrane, an important component in the skull/brain interface, in a computational brain model. Such an improved representation of the skull/brain interface will enhance the accuracy of finite element models used in brain injury mechanism studies under various loading conditions.


Assuntos
Aracnoide-Máter/fisiologia , Modelos Biológicos , Pia-Máter/fisiologia , Animais , Fenômenos Biomecânicos , Bovinos , Elasticidade , Estresse Mecânico , Viscosidade
7.
J Clin Neurosci ; 20(2): 301-5, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23219826

RESUMO

Subdural effusion sometimes occurs during neurosurgery after opening the Sylvian fissure, due to cerebrospinal fluid (CSF) leakage from the torn arachnoid membrane. Unexpected bleeding from the fragile bridging veins may also result from brain retraction. Neurosurgeons must always watch carefully for these complications during surgery. To prevent such complications, we have attempted the clinical application of a polysaccharide nanosheet that is semi-absorbent and has a potent physical adhesive strength to investigate its therapeutic utility for arachnoid plasty and enhancement of bridging vein tensile strength in Sprague-Dawley rats. The use of overlapping nanosheets completely prevented CSF leakage from injured arachnoid membranes in the cerebral cortex. No inflammatory infiltration was observed on the cerebral surface after 6 months of follow up. In addition, the use of nanosheet bandages significantly reinforced venous tensile strength. This reinforcement increased with the number of overlaid nanosheets. We report that polysaccharide nanosheets can be used for arachnoid plasty without chemical bonding agents and for reinforcement of venous tensile strength in rat vessels. Nanosheets may be an effective neurosurgical tool.


Assuntos
Aracnoide-Máter/cirurgia , Microcirurgia/métodos , Nanotecnologia/métodos , Procedimentos Neurocirúrgicos/métodos , Polissacarídeos/uso terapêutico , Resistência à Tração , Animais , Aracnoide-Máter/citologia , Aracnoide-Máter/fisiologia , Masculino , Polissacarídeos/administração & dosagem , Ratos , Ratos Sprague-Dawley , Resistência à Tração/fisiologia
8.
Neuroscience ; 177: 23-34, 2011 Mar 17.
Artigo em Inglês | MEDLINE | ID: mdl-21195136

RESUMO

Modeling the behavior of mammalian arachnoid cells is critical to understand hydrocephalus and other brain disorders involving abnormal flow of cerebrospinal fluid, yet relatively little is known about the physiology of arachnoid cells due to lack of a robust three-dimensional model system. Explanted primary cultures have been the only option to study transport across arachnoid cell membranes, but practical limitations of primary culture include slow growth, early senescence, and poor reproducibility. The purpose of this study was to create immortalized rat arachnoid cell lines to permit in vitro study of arachnoid granulations and properties of cerebrospinal fluid (CSF) flow. We established and partially characterized two immortalized cell lines generated from primary rat arachnoid cells, using retroviral gene transfer of SV40 large T antigen (SV40 LTAg) either with or without human telomerase (hTERT). The established cell lines stably express either SV40 LTAg alone, or SV40 LTAg and hTERT, and demonstrate high proliferative rate, contact inhibition at confluence, and stable expression of protein markers characteristic of native arachnoid cells over more than 160 passages.


Assuntos
Aracnoide-Máter/citologia , Aracnoide-Máter/fisiologia , Técnicas de Transferência de Genes , Espaço Subaracnóideo/fisiologia , Animais , Técnicas de Cultura de Células/métodos , Linhagem Celular Transformada , Líquido Cefalorraquidiano/citologia , Líquido Cefalorraquidiano/fisiologia , Pressão do Líquido Cefalorraquidiano/fisiologia , Feminino , Humanos , Ratos , Ratos Sprague-Dawley , Espaço Subaracnóideo/citologia
9.
J Biomech ; 44(3): 467-74, 2011 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-21087768

RESUMO

Traumatic brain injury (TBI) has become a major public health and socioeconomic problem that affects 1.5 million Americans annually. Finite element methods have been widely used to investigate TBI mechanisms. The pia-arachnoid complex (PAC) covering the brain plays an important role in the mechanical response of the brain during impact or inertial loading. Existing finite element brain models have tended to oversimplify the response of the PAC due to a lack of accurately defined material properties of this structure, possibly resulting in a loss of accuracy in the model predictions. The objectives of this study were to experimentally determine the material properties of the PAC under shear loading. Bovine PAC was selected in the current study in view of its availability and comparability with previous studies. Tangential shear tests were conducted at 0.8, 7.3, and 72 s(-1). The mean shear moduli were 11.73, 20.04, and 22.37 kPa at the three strain rates tested. The ultimate stress, at the three strain rates, was 9.21, 17.01, and 22.26 kPa, while the ultimate strain was 1.52, 1.58, and 1.81. Results from the current study provide essential information to properly model the PAC membrane, an important component in the skull/brain interface, in a computational model of the human/animal head. Such an improved representation of the in vivo skull/brain interface will enhance future studies investigating brain injury mechanisms under various loading conditions.


Assuntos
Aracnoide-Máter/fisiologia , Pia-Máter/fisiologia , Estresse Mecânico , Animais , Fenômenos Biomecânicos , Lesões Encefálicas/fisiopatologia , Bovinos , Análise de Elementos Finitos , Crânio/fisiologia , Resistência à Tração/fisiologia
10.
Acta Neurochir (Wien) ; 153(1): 191-200, 2011 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-20936312

RESUMO

OBJECT: Liliequist's membrane (LM) is an important arachnoid structure in the basal cisterns. The relevant anatomic descriptions of this membrane and how many leaves it has are still controversial. The existing anatomical theories do not satisfy the needs of minimally invasive neurosurgery. We aimed to establish the three-dimensional configuration of LM. METHODS: Fifteen adult formalin-fixed cadaver heads were dissected under a surgical microscope to carefully observe the arachnoid mater in the suprasellar and post-sellar areas and to investigate the arachnoid structure and its surrounding attachments. RESULTS: It was found that the LM actually consists of three types of membranes. The diencephalic membrane (DM) was usually attached by the mesencephalic membrane (MM) from underneath, and above DM it was usually a pair of hypothalamic membranes (HMs) extending superomedially. The pair of HMs was stretched between the DM (or MM) and the hypothalamus and were seldom attached to the carotid-chiasmatic walls between the carotid cistern and the chiasmatic cistern. These three types of membranes (DM, MM, and HM) comprised the main arachnoid structure in the anterior incisural space and often presented as four connected leaves. However, only two thirds of the specimens had all three types of membranes, and there was considerable variation in the characteristics and shapes of the membranes among the specimens. CONCLUSION: All three types of membranes comprising LM serve as important anatomical landmarks and interfaces for surgical procedures in this area.


Assuntos
Aracnoide-Máter/anatomia & histologia , Encéfalo/anatomia & histologia , Fossa Craniana Média/anatomia & histologia , Base do Crânio/anatomia & histologia , Espaço Subaracnóideo/anatomia & histologia , Aracnoide-Máter/fisiologia , Encéfalo/fisiologia , Cadáver , Fossa Craniana Média/fisiologia , Humanos , Base do Crânio/fisiologia , Espaço Subaracnóideo/fisiologia
11.
J R Soc Interface ; 7(49): 1205-18, 2010 Aug 06.
Artigo em Inglês | MEDLINE | ID: mdl-20335192

RESUMO

The arachnoid membrane (AM) and granulations (AGs) are important in cerebrospinal fluid (CSF) homeostasis, regulating intracranial pressure in health and disease. We offer a functional perspective of the human AM's transport mechanism to clarify the role of AM in the movement of CSF and metabolites. Using cultures of human AG cells and a specialized perfusion system, we have shown that this in vitro model mimics the in vivo characteristics of unidirectional fluid transport and we present the first report of serum-free permeability values (92.5 microl min(-1) mm Hg(-1) cm(-2)), which in turn are in agreement with the CSF outflow rates derived from a dynamic, in vivo magnetic resonance imaging-based computational model of the subarachnoid cranial space (130.9 microl min(-1) mm Hg(-1) cm(-2)). Lucifer yellow permeability experiments have verified the maintenance of tight junctions by the arachnoidal cells with a peak occurring around 21 days post-seeding, which is when all perfusion experiments were conducted. Addition of ruthenium red to the perfusate, and subsequent analysis of its distribution post-perfusion, has verified the passage of perfusate via both paracellular and transcellular mechanisms with intracellular vacuoles of approximately 1 microm in diameter being the predominant transport mechanism. The comparison of the computational and in vitro models is the first report to measure human CSF dynamics functionally and structurally, enabling the development of innovative approaches to modify CSF outflow and will change concepts and management of neurodegenerative diseases resulting from CSF stagnation.


Assuntos
Aracnoide-Máter , Encéfalo/fisiologia , Imagem por Ressonância Magnética/métodos , Aracnoide-Máter/citologia , Aracnoide-Máter/metabolismo , Aracnoide-Máter/fisiologia , Transporte Biológico/fisiologia , Células Cultivadas , Simulação por Computador , Homeostase/fisiologia , Humanos , Técnicas In Vitro , Pessoa de Meia-Idade , Movimento , Perfusão , Crânio/metabolismo , Espaço Subaracnóideo/fisiologia
12.
Neurosurgery ; 65(4): 644-64; discussion 665, 2009 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-19834369

RESUMO

OBJECTIVE: A limitation of previous studies of the arachnoid cisterns and membranes is that the act of opening the sylvian and interhemispheric fissures and basal arachnoid often led to destruction of the cisternal compartments and their membranous walls. The goal of this study was to overcome this limitation by combining the surgical microscope and endoscope for the examination of the cisternal compartments and their membranous walls. METHODS: The supratentorial cisterns were examined in 22 cadaveric brains using both the operating microscope and the endoscope. RESULTS: There are 2 types of arachnoid membranes: outer and inner. The outer arachnoidal membrane surrounds the whole brain, and the inner membranes divide the subarachnoid space into cisterns. Twelve inner arachnoid membranes were identified in the supratentorial area: diencephalic, mesencephalic, medial carotid, intracarotid, intracrural, olfactory, medial and lateral lamina terminalis, and proximal, medial, intermediate, and lateral sylvian membranes. These membranes partially or completely separate the subarachnoid space into 9 supratentorial cisterns: sylvian, carotid, chiasmatic, lamina terminalis, pericallosal, crural, ambient, oculomotor, and interpeduncular. There is a confluent area between the carotid, interpeduncular, and crural cisterns, which frequently has no membrane separating these cisterns. CONCLUSION: Twelve inner arachnoid membranes and 9 cisterns were identified in this study.


Assuntos
Aracnoide-Máter/anatomia & histologia , Encéfalo/anatomia & histologia , Cisterna Magna/anatomia & histologia , Dissecação/instrumentação , Dissecação/métodos , Endoscópios , Espaço Subaracnóideo/anatomia & histologia , Aracnoide-Máter/fisiologia , Encéfalo/fisiologia , Cadáver , Líquido Cefalorraquidiano/fisiologia , Cisterna Magna/fisiologia , Endoscopia/métodos , Humanos , Microcirurgia/instrumentação , Microcirurgia/métodos , Espaço Subaracnóideo/fisiologia
13.
Tissue Eng ; 13(6): 1269-79, 2007 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-17518753

RESUMO

PURPOSE: To culture physiologically functional primary arachnoidal cells on a suitable polymer substrate for an in-vitro model of the cerebrospinal fluid outflow pathway. METHODS: Primary cultures of arachnoidal cells were prepared within 24 hours post-mortem from brain tissue obtained from human cadavers at autopsy. Arachnoidal cells were characterized using immunocytochemistry and seeded onto needle punched non-woven poly(ethylene terephthalate)(PET) scaffolds. Metabolic rate, cell growth rate in log phase, morphologic assessment, immunocytochemistry, and protein analysis were used to characterize the cultures in both 2-D and 3-D-culture. Functional outflow assessment was performed using the Lucifer Yellow (LY) permeability assay and hydraulic conductivity (Lp) determination. RESULTS: Cells cultured on PET scaffold grew slightly slower than cells grown in 2-D-culture as measured by metabolic rate and growth rate, however, they often formed sheets that bridged between the adjacent scaffold filaments forming many junctional protein connections. LY permeability coefficients of 2-D cells were compared with cells from scaffolds, and were not significantly different (p > 0.05) for both culture conditions. Average Lp of cells from 2-D-culture and 3-D-scaffolds were compared and shown not to be significantly different. CONCLUSION: Based on the biochemical and functional analysis, it has been shown that cells cultured on 3D-PET scaffolds retained the same properties as cells from 2D-culture plates.


Assuntos
Aracnoide-Máter/citologia , Aracnoide-Máter/fisiologia , Matriz Extracelular/química , Polietilenotereftalatos/química , Engenharia Tecidual/métodos , Materiais Biomiméticos/química , Adesão Celular , Técnicas de Cultura de Células/métodos , Proliferação de Células , Células Cultivadas , Humanos , Permeabilidade
14.
Stapp Car Crash J ; 50: 637-49, 2006 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-17311181

RESUMO

The pia-arachnoid complex (PAC) covering the brain plays an important role in the mechanical response of the brain due to impact or inertial loading. However, the mechanical properties of the pia-arachnoid complex and its influence on the overall response of the brain have not been well characterized. Consequently, finite element (FE) brain models have tended to oversimplify the response of the pia-arachnoid complex, possibly resulting in a loss of accuracy in the model predictions. The aim of this study was to determine, experimentally, the material properties of the pia-arachnoid complex under quasi-static and dynamic loading conditions. Specimens of the pia-arachnoid complex were obtained from the parietal and temporal regions of freshly slaughtered bovine subjects with the specimen orientation recorded. Single-stroke, uniaxial quasi-static and dynamic tensile experiments were performed at strain-rates of 0.05, 0.5, 5 and 100 s(-1) (n = 10 for each strain rate group). Directional differences of the pia-arachnoid complex were also investigated. Results from this study revealed the pia-arachnoid complex was rate-dependent and isotropic, suggesting that the pia-arachnoid complex can provide omnidirectional support and load bearing to the adjacent brain tissue during an impact.


Assuntos
Aracnoide-Máter/fisiologia , Modelos Neurológicos , Estimulação Física/métodos , Pia-Máter/fisiologia , Animais , Fenômenos Biomecânicos/métodos , Bovinos , Simulação por Computador , Elasticidade , Técnicas In Vitro , Estresse Mecânico , Resistência à Tração/fisiologia , Viscosidade
15.
Cancer Treat Res ; 125: 1-16, 2005.
Artigo em Inglês | MEDLINE | ID: mdl-16211880

RESUMO

The arachnoid membrane and pia mater are the two membranous layers that comprise the leptomeninges. Cerebrospinal fluid is made within the ventricular system by cells of the choroid plexus and ependyma. This chapter describes in detail the normal anatomic structure and physiologic interactions of the cerebrospinal fluid and leptomeningeal space that are critical to our understanding and treatment of leptomeningeal metastases.


Assuntos
Aracnoide-Máter/anatomia & histologia , Aracnoide-Máter/fisiologia , Líquido Cefalorraquidiano/citologia , Líquido Cefalorraquidiano/fisiologia , Espaço Subaracnóideo/anatomia & histologia , Espaço Subaracnóideo/fisiologia , Ventrículos Cerebrais/anatomia & histologia , Ventrículos Cerebrais/fisiologia , Plexo Corióideo/anatomia & histologia , Plexo Corióideo/fisiologia , Epêndima/anatomia & histologia , Epêndima/fisiologia , Humanos , Medula Espinal/anatomia & histologia , Medula Espinal/fisiologia
17.
Expert Opin Biol Ther ; 4(8): 1191-201, 2004 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-15268655

RESUMO

The choroid plexus (CP) produces cerebrospinal fluid (CSF) and forms the blood-CSF barrier. However, the CP may have additional functions in the CNS beyond these traditional roles. Preclinical and clinical studies in ageing and neurodegeneration demonstrate anatomical and physiological changes in CP, suggesting roles in normal and pathological conditions and potentially endogenous repair processes following trauma. One of the broadest functions of the CP is establishing and maintaining the extracellular milieu throughout the brain and spinal cord, in part by secreting numerous growth factors into the CSF. The endogenous secretion of growth factors raises the possibility that transplantable CP might enable delivery of these molecules to the brain, while avoiding the conventional molecular and genetic alterations associated with modifying cells to secrete selected products. This review describes some of the anatomical and functional changes of CP in ageing and neurodegeneration, and recent demonstrations of the therapeutic potential of transplanted CP for neural trauma.


Assuntos
Plexo Corióideo/fisiologia , Células Epiteliais/transplante , Fatores de Crescimento Neural/metabolismo , Adulto , Idoso , Envelhecimento/fisiologia , Doença de Alzheimer/patologia , Doença de Alzheimer/fisiopatologia , Animais , Apoptose , Aracnoide-Máter/fisiologia , Atrofia , Encéfalo/patologia , Lesões Encefálicas/fisiopatologia , Lesões Encefálicas/cirurgia , Isquemia Encefálica/patologia , Isquemia Encefálica/fisiopatologia , Líquido Cefalorraquidiano/metabolismo , Plexo Corióideo/citologia , Plexo Corióideo/metabolismo , Plexo Corióideo/patologia , Plexo Corióideo/ultraestrutura , Indução Enzimática , Humanos , Camundongos , Camundongos Transgênicos , Pessoa de Meia-Idade , Doenças Neurodegenerativas/fisiopatologia , Ratos , Regeneração , Traumatismos da Medula Espinal/fisiopatologia , Traumatismos da Medula Espinal/cirurgia
18.
Folia Morphol (Warsz) ; 62(3): 255-7, 2003.
Artigo em Inglês | MEDLINE | ID: mdl-14507060

RESUMO

UNLABELLED: Numerous fibrous elements known as the Willis chords are situated in the light of the superior sagittal sinus. The paper is aimed at a comparative evaluation of the appearance of the Willis chords appearing in the superior sagittal sinus during various periods of human life and a determination of their role. The material comprises 200 brains at the foetal period as well as 200 adult and senile brains. The experimental methods include injection methods, infrared light, the Pickworth method and computer image analysis. During adulthood, various elements such as valvulae, divisions, plates, beams and arachnoidal granulation are situated in the light of superior sagittal sinus. The number of arachnoidal granulations increases continuously due to age, new ones appearing close to those already in existence and old granulation spreading. The superior sagittal sinus contains numerous valvulae similar to the feedback flaps typical for hydraulic systems. Divisions act as orifices which lead to a fall in pressure and induce blood into the sinus. Large differences between the cross-sections of meningeal veins and bridge veins were noticed, which resembles the structure of ejector. The blood flow in the bridge veins ending at the superior sagittal sinus is controlled by the valvulae and their geometrical form changes according to age. CONCLUSION: The Willis chords situated in the superior sagittal sinus may control the circulation. Their number grows with age and their morphology changes.


Assuntos
Aracnoide-Máter/embriologia , Veias Cerebrais/embriologia , Cavidades Cranianas/embriologia , Adulto , Idoso , Envelhecimento/fisiologia , Aracnoide-Máter/crescimento & desenvolvimento , Aracnoide-Máter/fisiologia , Veias Cerebrais/crescimento & desenvolvimento , Veias Cerebrais/fisiologia , Pressão do Líquido Cefalorraquidiano/fisiologia , Circulação Cerebrovascular/fisiologia , Cavidades Cranianas/crescimento & desenvolvimento , Cavidades Cranianas/fisiologia , Feto , Humanos
19.
Arq Neuropsiquiatr ; 61(3A): 561-5, 2003 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-14513158

RESUMO

The arachnoid granulations of adult individual of both sexes were studied through scanning electron microscopy. The dura mater and arachnoid meninges of individuals were collected at the Service of Death Verification of São Paulo - USP and fixed in Karnovsky solution. After this period the material was prepared for analysis in electron microscope. Our results demonstrated that the arachnoid granulations are formed by a pedicle, body and apex, being surrounded by a capsule of connective tissue, which in turn is composed of, basically, bundles of collagen fibers that line pores of different shapes and sizes. The smaller pores are lined by tiny bundles and are located at the apical region of the granulation and the larger are lined by thicker bundles and are located at the lateral regions. In the body we verified that the bundles of collagen fibers compose a fibrous meshwork and in some regions these bundles have circular orientation, forming pores similar to those found at the region of the capsule.


Assuntos
Aracnoide-Máter/ultraestrutura , Colágeno/ultraestrutura , Fibras Nervosas/ultraestrutura , Absorção , Adulto , Idoso , Idoso de 80 Anos ou mais , Aracnoide-Máter/fisiologia , Líquido Cefalorraquidiano/fisiologia , Dura-Máter/ultraestrutura , Tecido Elástico/fisiologia , Tecido Elástico/ultraestrutura , Humanos , Microscopia Eletrônica de Varredura , Pessoa de Meia-Idade , Fibras Nervosas/fisiologia
20.
Lymphat Res Biol ; 1(1): 41-4; discussion 45, 2003.
Artigo em Inglês | MEDLINE | ID: mdl-15624320

RESUMO

Despite the fact that the central nervous system parenchyma does not contain lymphatics, extracranial lymphatic vessels play a very important role in volumetric cerebrospinal fluid (CSF) transport. The most important extracranial location at which lymphatics gain access to CSF is in the nasal submucosa after CSF convects through the cribriform plate. At relatively low intracranial pressures (ICPs), the majority of cranial CSF absorption occurs through this pathway. Global CSF transport parameters in the late gestation fetus and adult sheep are very similar, even though significant numbers of arachnoid projections seem to exist only in the adult. Therefore, extracranial lymphatic vessels play an important role in CSF transport before birth and may represent the primary mechanism for CSF absorption in the neonate. Based on these considerations, hydrocephalus may involve reduced CSF transport to, or into extracranial lymphatic absorption sites.


Assuntos
Aracnoide-Máter/fisiologia , Líquido Cefalorraquidiano/fisiologia , Sistema Linfático/fisiologia , Vasos Linfáticos/fisiologia , Absorção , Animais , Transporte Biológico , Pressão do Líquido Cefalorraquidiano , Humanos , Hidrocefalia , Recém-Nascido , Modelos Biológicos , Modelos Teóricos , Pressão , Fatores de Tempo , Água
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