RESUMEN
As the uterus enlarges to accommodate the growing fetus during pregnancy, the cervix behaves essentially as a barrier. During ripening and delivery, it needs to become soft and distensible to allow dilation and the passage of the conceptus. As the transformations of the collagen-containing fibres are known to be essential for ripening and delivery, it has been hypothesized that the elastic system fibres, owing to their intrinsic mechanical properties (reversible extensibility), could be involved in the shape-recovering process immediately after delivery. In sections stained by Weigert's resorcin-fuchsin (with previous oxidation), we describe the elastic system fibres in the lamina propria of the rat uterine cervix. They are distributed following different patterns when in the endocervix or in the ectocervical-vaginal region. A third distinctive pattern (named the 'elastic tendon') is described here for the first time in the uterine-cervical transition. A special morphometrical protocol has been designed in order to overcome problems during the quantification process. Using the so-called intercept counting method, it was possible to demonstrate that the elastic system fibres are increased in the cervix at the end of pregnancy. They may be involved in the immediate shape-recovering of the cervix after delivery as well as in helping to strengthen the anchoring of the epithelium to the lamina propria, thus minimizing birth trauma.
Asunto(s)
Cuello del Útero/anatomía & histología , Tejido Elástico/anatomía & histología , Procesamiento de Imagen Asistido por Computador , Preñez/fisiología , Animales , Colorantes , Femenino , Embarazo , Ratas , Ratas Wistar , Coloración y Etiquetado/métodos , Útero/anatomía & histologíaRESUMEN
The uterine cervix is a dynamic structure with a high capacity to adapt to different, even opposing, roles during the sequence of physiological events of gestation (for example, acting as a barrier to retain the fetus during pregnancy and dilating to allow delivery at term). Histoarchitectural changes of the uterine cervix allow its successful adaptation. The aim of this study was to investigate whether fibroblastic cell plasticity, described in the lamina propria of the rat uterine cervix at term, could be observed in women too. Biopsy specimens of non-pregnant and intrapartum human cervices were studied under the transmission electron microscope, and cytoskeletal differentiation markers were identified by immunohistochemistry under the light microscope. Desmin-positive cells were present in the mucous layer of the cervix during labour. These cells displayed cytoplasmic processes (typical of myofibroblasts) that also stained positively for vimentin. The main ultrastructural features for defining the myofibroblast under the electron microscope were also observed in these cells. However, cervices of non-pregnant women contained resident fibroblasts at the same location. Examination of the differentiation repertoire of fibroblastic cells in the mucous layer of the uterine cervix resulted in the characterization of myofibroblasts at term. The implications of the plasticity of fibroblastic-myofibroblastic cells in the physiological changes displayed in the uterine cervix during pregnancy, labour and postpartum involution require further investigation.
Asunto(s)
Cuello del Útero/fisiología , Fibroblastos/ultraestructura , Trabajo de Parto/fisiología , Moco/citología , Biomarcadores/análisis , Diferenciación Celular/fisiología , Cuello del Útero/ultraestructura , Citoesqueleto/química , Citoesqueleto/ultraestructura , Desmina/análisis , Femenino , Humanos , Inmunohistoquímica , Microscopía Electrónica , Mioblastos del Músculo Liso/ultraestructura , Embarazo , Vimentina/análisisRESUMEN
Different organs contain fibroblasts with specific features and functions, indicating the complexity of fibroblast biology. In the rat cervical stroma, fibroblasts are preferentially located in the fibrous ring that surrounds the mucous layer. The purpose of this study was to investigate the morphological features and immunophenotype of fibroblastic cells of the uterine cervix in cycling, pregnant, and postpartum rats. Expression of the cytoskeletal proteins desmin, vimentin, and alpha-smooth muscle actin (alpha-SMA) were studied by immunohistochemistry. The optical density of immunohistochemical staining was quantified by image analysis. The ultrastructural features of fibroblastic cells were observed under transmission electron microscopy. Cervical fibroblastic cells always expressed vimentin and desmin but never alpha-SMA. During the first half of pregnancy (Day 5 [D5] to D14), desmin intensity values were similar to those of cycling and postpartum fibroblasts. In contrast, a strong expression of desmin was found from D15 to D22, with maximal expression at term (D23). Immunohistochemical expression for vimentin was constant throughout pregnancy and showed no differences with cycling and postpartum uterine cervices. Stromal cells from cycling and early pregnant rats displayed ultrastructural features characteristic of typical fibroblasts. In contrast, at the end of pregnancy, fibroblasts differentiated and showed increased secretory characteristics, reaching the ultrastructural features of a myofibroblast. Based on the differential expression of desmin and the electron microscopic observations, the foregoing results showed a modulation of the fibroblastic phenotype in the uterine cervix during pregnancy. To our knowledge, this is the first report that addresses the presence of myofibroblasts derived from resident fibroblasts in the fibrous ring of the rat uterine cervix. Fibroblastic-myofibroblastic cell plasticity may have implications in the physiological changes displayed in the uterine cervix during pregnancy, parturition, and postpartum involution.
Asunto(s)
Cuello del Útero/citología , Fibroblastos/química , Fibroblastos/ultraestructura , Trabajo de Parto , Actinas/análisis , Animales , Tamaño de la Célula , Desmina/análisis , Femenino , Fibroblastos/fisiología , Inmunohistoquímica , Microscopía Electrónica , Orgánulos/ultraestructura , Embarazo , Ratas , Ratas Wistar , Vimentina/análisisRESUMEN
Growth and differentiation of mammary gland is associated with numerous hormones and a variety of cell-cell, cell-matrix interactions. This study addressed the role of relaxin (Rlx) on these processes. Morphologic and biochemical changes that occur throughout the second half of pregnancy are reported. Temporal patterns and spatial distributions of markers useful to evaluate proliferation, secretion, and collagen remodeling were established. To evaluate the role of Rlx, an ablation/replacement animal model was used. Considering Rlx secretion pattern, two periods were selected: d 11 through d 13, and d 20 through d 23. In the stroma, the extracellular compartment showed changes associated with the lack of Rlx. Collagen remodeling within the lobuloalveolar structure, measured by a significant increase in collagen birefringence, decreased at d 12, d 21, and d 22. Parenchymal structures were less sensitive to the absence of Rlx than stroma. Epithelial cell proliferation was lower in Rlx-deficient rats only at d 12, and alpha-lactalbumin expression decreased at d 21 and d 22. Both lobuloalveolar diameter and percentage of area occupied by these structures showed no changes. In the absence of Rlx, some of the studied markers showed statistically significant differences in scattered days; these do not make clear trends. No differences were found on d 23 on any of the studied parameters suggesting that compensatory mechanisms might be activated to overcome the effects of the absence of Rlx. Unlike the critical role of Rlx either in uterine cervix dilation or in nipple development during rat pregnancy, Rlx had a minor role in growth and differentiation of rat mammary gland.
Asunto(s)
Diferenciación Celular/fisiología , Glándulas Mamarias Animales/crecimiento & desarrollo , Preñez/fisiología , Relaxina/fisiología , Animales , Antimetabolitos/farmacología , Bromodesoxiuridina/farmacología , Colágeno/metabolismo , Femenino , Inmunohistoquímica , Lactalbúmina/inmunología , Lactalbúmina/metabolismo , Glándulas Mamarias Animales/citología , Ovariectomía , Embarazo , Ratas , Ratas WistarRESUMEN
The pubic joint of male and female rats was studied at the light- and electron microscopical levels using methods that selectively disclose the extracellular matrix fibres and glycosaminoglycans. The interpubic tissue showed no difference between sexes (including pregnant and intrapartum females). The medial ends of the pubic bones were covered by articular caps of hyaline cartilage that blended in the midline. The whole articular cartilage was covered dorsally and ventrally (as well as craneally and caudally) by a typical perichondrium. The differential distribution of the fibres of the collagenous and elastic systems in the pubic joint agreed with the results reported in the literature for other rat cartilages. Collagen fibres, composed mainly of type-I collagen, were localised to the fibrous perichondrium and bone. Type-II collagen was localised to the central nucleus of hyaline cartilage, whereas reticulin fibres (rich in type-III collagen) were found in the adventitial loose connective tissue adherent to the most superficial layer of the perichondrium. The central nucleus of hyaline cartilage possessed the two types of elastic-related fibres: elaunin fibres were localised mainly to the chondrogenic layer of the perichondrium, whereas oxytalan fibres were found in the matrix that surrounded the chondrocytes. The bulk of the glycosaminoglycans present in the pubic joint cartilage corresponded to hyaluronic acid and chondroitin sulphate. The propriety of classification of the rat pubic joint as a true synchondrosis (instead of symphysis), and the fact that the unaltered pelvis of the rat seems to be adequate for normal parturition, are discussed.
Asunto(s)
Cartílago Articular/metabolismo , Matriz Extracelular/metabolismo , Glicosaminoglicanos/metabolismo , Sínfisis Pubiana/metabolismo , Ratas Wistar/metabolismo , Animales , Cartílago Articular/ultraestructura , Colágeno Tipo I/metabolismo , Colágeno Tipo I/ultraestructura , Colágeno Tipo II/metabolismo , Colágeno Tipo II/ultraestructura , Colágeno Tipo III/metabolismo , Colágeno Tipo III/ultraestructura , Proteínas Contráctiles/metabolismo , Matriz Extracelular/ultraestructura , Proteínas de la Matriz Extracelular/metabolismo , Femenino , Masculino , Embarazo , Sínfisis Pubiana/ultraestructura , Ratas , Factores SexualesRESUMEN
AIMS: Pulmonary fibrosis in acute and chronic lung disease has been much investigated, but little attention has been directed at the elastic tissue in these situations. Our aim was to verify whether elastic deposition accompanies collagen deposition in the repairing process of acute and chronic lung injury. METHODS AND RESULTS: We measured, by image analysis, the content of fibres of the collagenous and elastic systems of the alveolar septum in histological slides sampled from autopsied lungs, using the picrosirius-polarization method and Weigert's resorcin-fuchsin stain, respectively. Five groups were studied: I, 10 normal patients; II, 10 patients with cardiogenic pulmonary oedema; III, 23 adult respiratory distress syndrome (ARDS) patients in the early phase; IV, 14 ARDS patients in the late fibroproliferative phase; and V, 10 idiopathic pulmonary fibrosis patients. The first two groups were used as controls. The content of fibres of the collagenous and elastic systems was significantly increased in groups IV and V as compared to the other groups. CONCLUSIONS: Our results indicate that deposition of elastic system fibres is present in the fibroproliferative phase of ARDS and in usual interstitial pneumonia and suggest that this event may contribute to the alveolar mechanical dysfunction and remodelling that occur in acute and chronic interstitial lung disease.
Asunto(s)
Tejido Elástico/patología , Enfermedades Pulmonares Intersticiales/patología , Fibrosis Pulmonar/patología , Síndrome de Dificultad Respiratoria/patología , Enfermedad Aguda , Adolescente , Adulto , Anciano , Enfermedad Crónica , Colágeno/metabolismo , Tejido Elástico/metabolismo , Humanos , Procesamiento de Imagen Asistido por Computador , Enfermedades Pulmonares Intersticiales/metabolismo , Persona de Mediana Edad , Edema Pulmonar/metabolismo , Edema Pulmonar/patología , Fibrosis Pulmonar/metabolismo , Síndrome de Dificultad Respiratoria/metabolismo , Estudios RetrospectivosRESUMEN
Regenerating tail fins were studied in two species of teleosts, Tilapia rendalli and Cyprinus carpio, treated with indomethacin, aspirin, dexamethasone, penicillamine, and beta-aminoproprionitrile, drugs known to disrupt collagen metabolism in mammals. Collagen was studied under the light microscope by the Picrosirius-polarization method and also under the electron microscope. In general, these drugs disturbed the deposition and organization of collagen fibrils leading to abnormally thin or practically absent lepidotrichia and actinotrichia, and also to disorganized fibrous connective tissue. The resulting disorganization of the collagenous scaffolding of the regenerating dermoskeleton was probably responsible for a secondary effect on blastema distalization and on the general fin ray patterning that were also observed. The foregoing observations suggest that the stromal histoarchitecture of the regenerate plays a vital role in fin regeneration and indicate that these drugs may be useful in studying the extracellular matrix-cell interactions at the cellular and molecular level. In addition, the present findings provide a basis for developing different biological models by using teleost fin regeneration.
Asunto(s)
Colágeno/fisiología , Regeneración , Cola (estructura animal)/citología , Aminopropionitrilo/farmacología , Animales , Antiinflamatorios/farmacología , Antiinflamatorios no Esteroideos/farmacología , Antídotos/farmacología , Aspirina/farmacología , Carpas , Dexametasona/farmacología , Indometacina/farmacología , Penicilamina/farmacología , Regeneración/efectos de los fármacos , Cola (estructura animal)/fisiología , TilapiaRESUMEN
A challenge that research managers have to face is how to "reallocate" agency budgets in order to bring them in line with the results of performance reviews. Research policies must develop a strategic plan describing their goals, devise yardsticks to measure their progress, and tie that performance to allocate research funds with some degree of priority. Though Brazil already has a substantial presence in world's science, scientific enterprise must be used to strengthen it. The first step should be to raise standards in Brazilian science by concentrating the resources on supporting excellence. A strategy to judge biomedical research productivity should include tactics to disclose whether the resulting publications have appeared in the field's most respected, peer-reviewed journals. A pilot project to road-test the above-discussed ideas on performance measurements was conducted at the Laboratories of Medical Research (Clinical Hospital, University of São Paulo School of Medicine). These Laboratories perform a vast proportion of biomedical research at the country's largest University. This article illustrates that confidence in fairness and consistency with which funds are now being allocated has helped to improve productivity, thus showing that this strategy is fruitful.
Asunto(s)
Bibliometría , Laboratorios de Hospital/economía , Apoyo a la Investigación como Asunto/economía , Investigación/economía , Brasil , Sistemas de Información , Laboratorios de Hospital/estadística & datos numéricos , Publicaciones Periódicas como Asunto/estadística & datos numéricos , Investigación/estadística & datos numéricos , Apoyo a la Investigación como Asunto/estadística & datos numéricosRESUMEN
Ripening of the rat cervix involves widespread collagenolysis that follows an eosinophilic leukocyte infiltration. The hormonal control of these events is not well understood. The aims of this study were to investigate the mechanism through which progesterone (P) and 17beta-estradiol (E(2)) modulate eosinophilic invasion and to determine if this event is protein synthesis mediated. Cervical eosinophilic invasion was measured in intact rats during the second half of pregnancy and compared with values from ovariectomized (O) pseudopregnant (PSP) rats treated with P and E(2) in doses that mimicked the levels of pregnancy. Other O-PSP rats were treated with an E(2) antagonist (tamoxifen) and the antiprogestin RU-486. To study the role of protein synthesis in eosinophilic invasion of the cervix, rats were treated with actinomycin-D (an inhibitor of mRNA synthesis), and animals were sacrificed on D21 or D22 to evaluate eosinophilic invasion. Rats treated with E(2) showed high levels of infiltration and tamoxifen blocked this E(2) effect. On the other hand, P antagonized the stimulatory effects of E(2) on eosinophilic invasion, however when the P and E(2) treated rats were injected with RU-486 the inhibitory effect of P was reversed. In intact pregnant rats a sharp rise in eosinophilic infiltration was detected on D23, 20 h after the fall of serum P. Finally, E(2) treated rats injected with actinomycin-D had no invasion of eosinophils. In conclusion, the estrogen-triggered eosinophil invasion is affected by the classic estrogen receptor antagonist tamoxifen and by the mRNA synthesis blocker actinomycin-D suggesting a genomic action of E(2). Furthermore, the estrogen effect is blocked by P and this inhibition is reversed by RU-486.
Asunto(s)
Cuello del Útero/fisiología , Quimiotaxis de Leucocito/fisiología , Eosinófilos/fisiología , Estrógenos/fisiología , Progesterona/fisiología , Animales , Maduración Cervical/fisiología , Quimiotaxis de Leucocito/efectos de los fármacos , Dactinomicina/farmacología , Antagonistas de Estrógenos/farmacología , Estrógenos/farmacología , Femenino , Mifepristona/farmacología , Inhibidores de la Síntesis del Ácido Nucleico/farmacología , Ovariectomía , Embarazo , Progesterona/farmacología , Seudoembarazo , Ratas , Ratas Wistar , Tamoxifeno/farmacologíaRESUMEN
The state of collagen aggregation in hepatic granulomas produced in experimental murine schistosomiasis and harvested at different phases of the disease was estimated by staining histological sections in Picrosirius and studying them under polarized light. Two different types of collagenous fibres appeared successively during granuloma evolution, the first population, of thin, weakly birefringent, greenish fibres being replaced by thicker collagen fibres which display a stronger yellow-red birefringence. A simple morphometric technique (a point-counting procedure) was used to quantify the two distinct populations of collagenous fibres. Curve-fitting procedures were then employed, using the state of collagen aggregation as the dependent variable and time as the independent variable. The results showed that there is a progressive organization of the collagenous scaffolding of hepatic granulomas, such that quantitative study of the degree of collagen organization allows an adequate determination of the age of each granuloma. The combination of the Picrosirius-polarization method with simple and efficient morphometric approaches will clearly provide useful information on the natural history of schistosomal granuloma scarring.
Asunto(s)
Colágeno/análisis , Granuloma/patología , Granuloma/parasitología , Cirrosis Hepática/parasitología , Parasitosis Hepáticas/patología , Esquistosomiasis mansoni/patología , Animales , Colorantes , Femenino , Ratones , Ratones Endogámicos , Microscopía de Polarización , Factores de TiempoRESUMEN
Cardiac performance is negatively associated with interstitial collagen in Chagas' cardiomyopathy. The magnitude of dysfunction is related to the degree of collagen, and this association seems to exhibit a threshold above it if definite cardiac deterioration occurs.
Asunto(s)
Enfermedad de Chagas/patología , Enfermedad de Chagas/fisiopatología , Colágeno , Miocardio/patología , Adulto , Femenino , Fibrosis/diagnóstico , Corazón/diagnóstico por imagen , Humanos , Masculino , Persona de Mediana Edad , Ventriculografía con RadionúclidosRESUMEN
The elastic system fibers were studied at the light microscopic level by using Weigert's resorcin-fuchsin method after oxidation. This study was designed to describe the distribution of these fibers in intrapulmonary guinea-pig airways and to characterize their conformational changes during bronchoconstriction induced by methacholine aerosol. Airways present a palisade of elastic system fibers just beneath the epithelial basement membrane; these fibers are also present in the adventitial connective tissue. Thin fibers link the fibers located in the palisade among themselves and also connect them to those fibers located in the bronchial adventitial tissue, by traversing the airway smooth muscle. During bronchoconstriction, the fibers located beneath the epithelial basement membrane are divided into two components: one follows the epithelial invaginations towards airway lumen, while the other population remains attached through airway smooth muscle to the fibers located in the adventitial connective tissue. At the ultrastructural level, the findings corroborated those of the light microscopy and in addition, disclosed that typical mature elastic fibers and also elaunin fibers attach directly to the basal lamina, a feature that has not been reported previously in other tissues studied. This configuration is compatible with the idea that fibers of the elastic system restrict the mucosal folding during bronchoconstriction, and may also provide energy to restore airway configuration to its normal status after contraction.
Asunto(s)
Bronquios/citología , Broncoconstricción/efectos de los fármacos , Broncoconstrictores/administración & dosificación , Tejido Elástico/citología , Pulmón/citología , Cloruro de Metacolina/administración & dosificación , Animales , Tejido Elástico/efectos de los fármacos , Cobayas , Microscopía ElectrónicaRESUMEN
Fibers of the collagenous and elastic systems are most relevant in the double mechanical action of visceral pleura (VP), i.e. volume limitation and the generation of elastic recoil pressure. In this work we studied the organization of these fibrous components of VP in two situations: normal lungs and bullous disease. We employed histochemical methods on conventional histological slides and on thin spreads of whole mounts of visceral pleura. In addition, the scanning electron microscope was also used. According to our results, pleural function is made possible by the combination of both the elastic and collagenous fiber systems, each one having as intrinsic organizational pattern. Marked alterations of pleural bullous structure are observed with changes in lung volume. Fibers of the elastic and collagenous systems are clearly interdependent elements. Collagenous fibers are interwoven in a plaited structure that closely resembles the osiers of a wicker basket, indicating that collagen fibers allow for lung volume increase up to a point of maximal stretching of the system. The pleural contribution to lung elastic recoil pressure originates from the elastic network which turns back to its resting position when inspiratory pressures are negligible. The pleural immobility in bullous disease is associated with an almost complete absence of elastic fibers and the presence of very thick collagen fibers, suggestive of a cicatricial process, devoid of any characteristic pattern of distribution.
Asunto(s)
Colágeno/análisis , Tejido Elástico/citología , Pleura/citología , Tejido Elástico/patología , Tejido Elástico/ultraestructura , Técnicas Histológicas , Humanos , Microscopía Electrónica de Rastreo , Pleura/patología , Pleura/ultraestructura , Enfisema Pulmonar/patología , Valores de ReferenciaRESUMEN
This work was designed to verify if a simple quantitative procedure to estimate the state of collagen aggregation is useful in describing the natural history of a fibrous process. For this purpose sixteen cases of Lechiguana lesion were used. Histochemical evaluation of the collagen content and its state of aggregation was done by the Picrosirius-polarization method. Morphometric studies were done by means of a point-counting procedure, which allowed the determination of the areal fraction of thin and thick collagenous fibers within Lechiguana lesions collected at different times of clinical evolution (14 days through 8 months). Early lesions are characterized by thin collagenous fibers. This population of slender fibers decreases later on, when thick fibers become more prevalent. Curve fitting procedures were employed using the state of collagen aggregation as the dependent variable and time as the independent variable. The best fitting was obtained by linear and exponential functions. Statistical analysis indicates that the quantitative study of the degree of collagen organization allows an adequate determination of the time course of Lechiguana lesions. We concluded that simple determinations of collagen aggregation provide numerical data that may be useful to build mathematical models relating time of evolution of the disease to fibrosis.
Asunto(s)
Compuestos Azo/análisis , Enfermedades de los Bovinos/patología , Histocitoquímica/métodos , Microscopía de Polarización/métodos , Paniculitis/patología , Paniculitis/veterinaria , Picratos/análisis , Animales , Biopsia , Bovinos , Cicatriz/patología , Colágeno/química , Colorantes/análisis , Tejido Conectivo/patología , Fibrosis/patología , Matemática , Factores de TiempoRESUMEN
This paper investigates the association between air pollution and lung neoplasia in an animal model. The experimental exposures were done in two locations with different air pollution profiles: a polluted area (downtown São Paulo) and a "clean" environment (Atibaia). Swiss mice were employed and urethane (3 g/kg) was used as carcinogenic substance. Two experiments were performed: Experiment I was designed to verify whether air pollution acts as initiator and/or promoter of lung cancer, using 300 mice; Experiment II employed 250 animals and aimed to verify if the effects of air pollution on the development of lung tumors was dose dependent. A significant effect of air pollution in augmenting lung carcinogenecity induced by urethane was observed. This effect was shown to be dose-dependent and reproducible on two different occasions. In addition, morphometric studies revealed that pollution may influence tumor phenotype. These results support the hypothesis that air pollution plays a significant role in the development of lung tumors.
Asunto(s)
Contaminantes Atmosféricos/toxicidad , Carcinógenos/toxicidad , Neoplasias Pulmonares/inducido químicamente , Uretano/toxicidad , Animales , Femenino , Neoplasias Pulmonares/patología , Masculino , Ratones , Salud UrbanaRESUMEN
Sheep uterine cervices and cervical mucus were heavily infiltrated by neutrophils during labour, whereas samples of cervices obtained from non-pregnant controls had no infiltrate. The neutrophilic infiltrate of the sheep uterine cervix at term was not homogeneously distributed throughout the organ: luminal mucus contained more neutrophils than tissues which, in turn, displayed a differential distribution, the superficial subepithelial layer being more heavily infiltrated than the deeper submucous layers. A widespread collagenolysis was observed in the sheep uterine cervix at term. The homogeneous morphological aspect of degradation of collagen fibres throughout the whole cervical stroma contrasted with the above-mentioned differential distribution of neutrophils. On the basis of previous reports showing that collagenolysis follows the leukocytic invasion of human and rat cervices at term, a possible role for the neutrophilic infiltrate of the sheep uterine cervix is discussed.
Asunto(s)
Cuello del Útero/citología , Cuello del Útero/metabolismo , Colágeno/metabolismo , Trabajo de Parto/metabolismo , Neutrófilos/citología , Ovinos/metabolismo , Animales , Movimiento Celular/fisiología , Cuello del Útero/ultraestructura , Colágeno/ultraestructura , Femenino , Trabajo de Parto/fisiología , Microscopía Electrónica/métodos , Microscopía Electrónica/veterinaria , Microscopía de Polarización , Neutrófilos/fisiología , Neutrófilos/ultraestructura , Embarazo , Ovinos/fisiologíaRESUMEN
The distribution and conformational changes of the fibers of the collagenous and elastic systems in guinea pig airways after a contractile agonist challenge are described. We observed a distinct pattern of behavior within the mucosal fibers during bronchoconstriction. Part of the fibers of the two systems tend to follow the epithelial invaginations towards the airway lumen, while the remaining ones seem to be attached to the internal smooth muscle. These layers of fibers in the mucosa are interconnected to one another and to the adventitial network by slender fibers. We suggest that the configuration and behavior of these fibers during bronchoconstriction may contribute to airway reopening after the contractile stimulus has ceased. The possible role of this mechanism in the pathophysiology of human asthma is discussed.
Asunto(s)
Broncoconstricción/fisiología , Colágeno/fisiología , Tejido Elástico/fisiología , Elastina/fisiología , Animales , CobayasRESUMEN
The distribution and conformational changes of the fibers of the collagenous and elastic systems in guinea pig airways after a contractile agonist challenge are described. We observed a distinct pattern of behavior within the mucosal fibers during bronchoconstriction. Part of the fibers of the two systems tend to follow the epithelial invaginations towards the airway lumen, while the remaining ones seem to be attached to the internal smooth muscle. These layers of fibers in the mucosa are interconnected to one another and to the adventitial network by slender fibers. We suggest that the configuration and behavior of these fibers during bronchoconstriction may contribute to airway reopening after the contractile stimulus has ceased. The possible role of this mechanism in the pathophysiology of human asthma is discussed.
Asunto(s)
Cobayas , Animales , Broncoconstricción/fisiología , Colágeno/fisiología , Tejido Elástico/fisiología , Elastina/metabolismo , Asma/fisiopatología , Bronquios/ultraestructuraRESUMEN
The present study was designed to assess the influence of aqueous and nonaqueous fixatives on the quantitative estimation of collagen-proteoglycan interaction in tissue sections. Tissues containing different collagen types and distinct sulfated proteoglycan classes were isolated from pig costal cartilage, human skin, and the inner muscular layer of dog small intestine and fixed using aqueous or nonaqueous methods. The results showed that the best fixation method was exposure to paraformaldehyde gas. When using aqueous fixatives, proteoglycans were lost to different degrees among the various tissues analyzed, reflecting differences in chemical properties of proteoglycan classes and/or in their interactions with other matrix components such as collagen.
Asunto(s)
Colágeno/metabolismo , Fijadores/química , Formaldehído/química , Polímeros/química , Proteoglicanos/metabolismo , Animales , Perros , Humanos , Microtomía , PorcinosRESUMEN
We investigated the existence of functional subpopulations of thyrotropes in pituitary glands of male rats, also seeking to establish any correlation of thyrotropin secretion with morphometric data of secretory granules. Pituitary cells secreting thyrotropin were detected using a reverse hemolytic plaque assay. Population analysis of the plaque sizes (TSH secreted) of individual thyrotropes in control cultures from male rats revealed a unimodal frequency distribution. TRH added to the medium resulted in a shift to a bimodal distribution of sizes, consisting of small and large modes, but did not alter the fraction of plaque-forming thyrotropes. The plaque size of control cultures was the same as that of the fraction of TRH-stimulated thyrotropes forming small plaques. Because the extent of hemolysis is related to the amount of thyrotropin secreted by each individual thyrotrope, these results suggest that: a) all thyrotropes secrete thyrotropin even in the absence of a stimulatory dose of TRH; b) the thyrotrope subpopulation secreting small amounts of thyrotropin when incubated with TRH may be unresponsive to this stimulatory factor. After performing reverse hemolytic plaque assay, plaque-forming cells were subsequently processed for electron microscopy. Morphometric analysis of the secretory granules correlated well with plaque size (TSH secreted). It is thus concluded that the functional subtypes of thyrotropes can be recognized on the basis of their ultrastructural images.