Single Tubular Structure Research Articles

Epithelial polarity-driven membrane separation but not cavitation regulates lumen formation of rat eccrine sweat glands

BackgroundEach eccrine sweat gland (ESG) is a single-tubular structure with a central lumen, and the formation of hollow lumen in the initial solid cell mass is a key developmental process. To date, there are no reports on the mechanism of native ESG lumen formation. MethodsTo investigate the lumen morphogenesis and the lumen formation mechanisms of Sprague-Dawley (SD) rat ESGs, SD rat hind-footpads at E20.5, P1–P5, P7, P9, P12, P21, P28 and P56 were obtained. The lumen morphogenesis of ESGs was examined by HE staining and immunofluorescence staining for polarity markers. The possible mechanisms of lumen formation were detected by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) apoptosis assay and autophagy marker LC3B immunofluorescence staining, and further explored by ouabain intervention experiment. ResultsIn SD rat ESGs, the microlumen was formed at P1, and the small intact lumen with apical-basal polarity appeared at P3. The expression of apical marker F-actin, basal marker Laminin, basolateral marker E-cadherin was consistent with the timing of lumen formation of SD rat ESGs. During rat ESG development, apoptosis and autophagy were not detected. However, inhibition of Na+-K+-ATPase (NKA) with ouabain resulted in decreased lumen size, although neither the timing of lumen formation nor the expression of polarity proteins was altered. ConclusionsEpithelial polarity-driven membrane separation but not cavitation regulates lumen formation of SD rat ESGs. NKA-regulated fluid accumulation drives lumen expansion.

3-D Human Sperm Flagellum Tracing in Low SNR Fluorescence Images.

Tracing tubular structures from biomedical images is important for a wide range of applications. Particularly, the spermatozoon is an essential cell whose flagella have a tubular form. Its main function is to fertilize the egg, and the flagellum is fundamental to achieve this task which depends importantly on the dynamics of intracellular calcium ([Ca2+]i). Measuring [Ca2+]i along the flagellum in 3-D is not a simple matter since it requires: 1) sophisticated fluorescence imaging techniques dealing with low intensity and signal to noise ratio (SNR) and 2) tracing the flagellum's centerline. Most of the algorithms proposed to trace tubular structures have been developed for multi-branch structures not being adequate for single tubular structures with low SNR. Taking into account the prior knowledge that the flagellum is constituted by a single tubular structure, we propose an automatic method to trace and track multiple single tubular structures from 3-D images. First, an algorithm based on one-class classification allows enhancement of the flagellum. This enhanced 3-D image permits guiding an iterative centerline algorithm toward the flagellum's centerline. Each sperm is assigned an ID to keep track of it in 3-D . Our algorithm was quantitatively evaluated using a ground truth 564 semi-manual traces (six 3-D image stacks) comparing them to those obtained from state-of-the-art tubular structure centerline extraction algorithms. The qualitative and quantitative results show that our algorithm is extracting similar traces as compared with ground truth, and it is more robust and accurate to trace the flagellum's centerline than multi-branch algorithms.

A Mathematical Model for the Population Dynamics of Intestinal Microbiota: Obese Versus Healthy Gastrointestinal Tract

IntroductionThe term microbiota refers to a community of microorganisms that are located in a certain space that have a symbiotic relationship with the host cells, in this specific case the human gastrointestinal tract. This interaction provides support to the tract in different functional aspects such as trophic functions, protection (immune system) and metabolism. There has been evidenced that intestinal microbiota plays an important role in synthesis, metabolism, and other functions associated to the nutrients and micronutrients that can lead to healthy or obese patients. In this work we aimed to understand and model the population dynamics of the intestinal microbiota.MethodsA mathematical model was design based on the gastrointestinal tract seen as a single tubular structure composed of Esophagus, Stomach, Small intestine (Duodenum, Jejunum and ileum) and colon. Only one major phylum of microorganisms (Either Firmicutes or Bacteroidetes) was included according to anatomical and physiological characteristics and in terms of its relative abundance in each part of the tract. The model included the subject's diet and activity level as inputs. Parameters for the model were obtained from a literature review. The model was implemented in Matlab and produced microorganism distribution (i.e. spatial concentration). We model different diets and pathological conditions.ResultsThe model reveals an expected growth of either Firmicutes or Bacteriodetes associated with the amount of nutrient and carrying capacity of the gastrointestinal tract. These results are in agreement with several reports obtained from the literature. In addition, the model showed an interesting stabilization of bacterial population under some circumstances depending on the segment of the gastro intestinal tract. Bacterial population is sensitive to diet and exercise.ConclusionsThe model can be used to predict the population dynamics under different diets and furthermore could be implemented as an important tool for bariatric surgery patients. The model can also shed some light on how to prevent the progression from overweight to obese just by changing the diet understanding the dynamics of gastrointestinal tract population.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Foxc1 Ablated Mice Are Anhidrotic and Recapitulate Features of Human Miliaria Sweat Retention Disorder

Sweat glands are critical for thermoregulation. The single tubular structure of sweat glands has a lower secretory portion and an upper reabsorptive duct leading to the secretory pore in the skin. Genes that determine sweat gland structure and function are largely unidentified. Here we report that a Fox family transcription factor, Foxc1, is obligate for appreciable sweat duct activity in mice. When Foxc1 was specifically ablated in skin, sweat glands appeared mature, but the mice were severely hypohidrotic. Morphologic analysis revealed that sweat ducts were blocked by hyperkeratotic or parakeratotic plugs. Consequently, lumens in ducts and secretory portions were dilated, and blisters and papules formed on the skin surface in the knockout mice. The phenotype was strikingly similar to the human sweat retention disorder miliaria. We further show that Foxc1 deficiency ectopically induces the expression of keratinocyte terminal differentiation markers in the duct luminal cells, which most likely contribute to keratotic plug formation. Among those differentiation markers, we show that Sprr2a transcription is directly repressed by overexpressed Foxc1 in keratinocytes. In summary, Foxc1 regulates sweat duct luminal cell differentiation, and mutant mice mimic miliaria and provide a possible animal model for its study.

682 Foxc1 ablated mice are anhidrotic and recapitulate features of a sweat retention syndrome, miliaria

Sweat glands play a critical role in thermoregulation. The single tubular structure of sweat glands has a lower secretory portion and an upper reabsorptive duct leading to the secretory pore in the skin. The transcription factors that determine sweat gland structure and function are largely unidentified. Here we report that a Fox family transcription factor, Foxc1, is obligate for appreciable sweat duct activity in mice. When Foxc1 was specifically ablated in skin, sweat glands appeared mature, but the mice were severely hypohidrotic. Morphological analysis revealed that sweat ducts were blocked by hyperkeratotic or parakeratotic plugs. Consequently, lumens in ducts and secretory portions were dilated, and blisters and papules formed on the skin surface in the knockout mice. The phenotype was strikingly similar to the human sweat retention syndrome miliaria. We further found that Foxc1 deficiency ectopically induced the expression of keratinocyte terminal differentiation markers in the luminal duct cells, which most likely contributed to keratotic plug formation. In summary, Foxc1 regulates sweat duct luminal cell differentiation, and mutant mice may provide a model for miliaria.

Elaboration of small‐diameter vascular prostheses—Selection of appropriate sterilisation method

ABSTRACTThe aim of study is the elaboration of semi‐biodegradable, multilayered tubular structures as substitutes for the reconstruction of small diameter vascular prostheses (<6 mm). The inert external layer of the prostheses will be fabricated via the melt electrospinning of poly (l‐lactide‐co‐glycolide) (PLGA). The middle layer will be constructed from polypropylene (PP); the first prototype will be produced via melt electrospinning and the second using the melt blowing technique. The general aim of this stage of the research is the selection of a sterilisation technique that is appropriate for semi‐biodegradable, multilayered tubular structures. For this purpose, single tubular structures created via the melt electrospinning of PLGA or PP and melt blown tubular structures of PP were elaborated. The influence of steam, ethylene‐oxide (EO), and radiation sterilisation techniques on the elaborated microstructure of tubular structures was analyzed during this study. The effect of each sterilisation technique was evaluated using differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy/energy‐dispersive X‐ray spectroscopy analysis (SEM/EDS). The changes in average molecular weight (Mw) and crystallinity index (CI) of the PLGA tubular structures after EO and steam sterilisation were evaluated. The EO and steam sterilisation resulted in the complete destruction of PLGA tubular structures. Only the radiation sterilisation (accelerated electrons) did not influence on PLGA tubular structures morphology as well as thermal and chemical properties. FTIR and SEM/EDS analysis indicated that no changes in the chemical properties of PP tubular structures after each sterilisation occurred. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40812.

Morphological characteristics and developmental changes of the ovary in the tick Haemaphysalis longicornis Neumann

Haemaphysalis longicornis (Ixodida: Ixodidae) is an important vector of transovarially transmitted parasites of the genus Babesia (Piroplasmida: Babesiidae). In the present study, we investigated the morphological characteristics and developmental changes of the ovary of H. longicornis. We show that the ovary of H. longicornis has a single tubular structure and is surrounded by a tunica propria. There is a longitudinal groove along one side of the ovary. During feeding and after engorgement, great changes can be observed in the ovary of H. longicornis and two rapid growth phases can be detected. The number of major protein bands of the ovary is significantly increased from day 3 of feeding and reaches a maximum on the day of engorgement. Therefore, the great diversity of proteins in the ovaries of H. longicornis can facilitate the identification of new targets for vaccine development.

Experimental evaluation of the buckling phenomena in the new joint design for upper deck structure of a bridge

This paper is concerned with the experimental mechanical analysis of a new design of a joint for a main components of a upper deck of a road bridge. These components are subject to the compression state stress induced by the weight and the load acting on the road. Each upper deck of a bridge (positioned on each side of the bridge) is composed by four tubular structures that must be joint each together. The joint must to take in to account many aspects, for example that the length of each component is not the same (because, obviously, there is a mechanical tolerance). This phenomena induce different compression stress on each component and so is very important non only the critical buckling load but also the post buckling behaviour of the structure. It is very important that if a single tubular structure reaches the critical load of instability, it still has load capacity . This is to avoid that, in the case where a column reaches the instability, the entire load acting on a column increase the load on the remaining three. For this purpose many different geometrical solutions have been designed (elaborated by fem analyses and successively tested experimentally). This work reports the main experimental results on the best joint solution and how this increase the load capacity and the displacement respect to the solution without this flange.

Atomistic dynamics of deformation, fracture, and joining of individual single-walled carbon nanotubes

The tensile deformation process of individual single-walled carbon nanotubes (SWCNTs) was in situ observed with measurements of the mechanical properties by transmission electron microscopy combined with the functions of scanning probe microscopy. The values of Young's modulus, tensile stress and strain at the fracture of SWCNTs are $950\ifmmode\pm\else\textpm\fi{}130\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$, $25\ifmmode\pm\else\textpm\fi{}1\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$, and $0.30\ifmmode\pm\else\textpm\fi{}0.03$, respectively. It was shown that two tips of fractured SWCNTs can be recovered to produce a single tubular structure by contact under compressive force and bias voltage. The in situ observations also demonstrated the formation of carbon monatomic wires during the fracture process of SWCNTs.

Morphological, histological, and ultrastructural studies of the ovary of the cattle-tick Boophilus microplus (Canestrini, 1887) (Acari: Ixodidae)

This study presents the morphology of the ovary, as well as the dynamics of the vitellogenesis process in oocytes of the cattle-tick Boophilus microplus. The ovary of these individuals is of the panoistic type; therefore, it lacks nurse cells. This organ consists of a single tubular structure, continuous, and composed of a lumen delimitated by a wall of small epithelial cells with rounded nuclei. In this tick species, the oocytes were classified into six stages varying from I to VI and according to: cytoplasm appearance and presence of the germ vesicle, yolk granules, and chorion. Oocytes of various sizes and at different developmental stages remain attached to the ovary through a cellular pedicel until completing stage V. Afterwards, they are liberated into the lumen and from there to the exterior. Some oocytes (classified as type VI) showed an atypical appearance indicating that some of the cellular components would be undergoing a degenerative process and/or reabsorption.

Morphological characterization of the ovary and oocytes vitellogenesis of the tick Rhipicephalus sanguineus (Latreille, 1806) (Acari: Ixodidae)

This study presents the morphology of the ovary, as well as the process of the vitellogenesis in oocytes of the tick Rhipicephalus sanguineus. The ovary of these individuals is of the panoistic type; therefore, it lacks nurse cells. This organ consists of a single tubular structure, continuous, and composed of a wall formed by small epithelial cells with rounded nuclei which delimit the lumen. The oocytes in the different developmental stages in this tick species were classified into five stages (I–V). They remain attached to the ovary during vitellogenesis by a cellular pedicel and afterwards the mature oocytes (stage V) are released into the ovary lumen.

CONJOINT CORPORA CAVERNOSA AND ITS ROLE IN ERECTION

The two penile corpora cavernosa (CC) remain as separate structures along the penile shaft. During our study of 28 cadavers, we came across three cadavers in which the two CCs were fused together forming a single tubular structure; this article discusses these three cadaveric specimens. The cadavers were aged 52, 36, and 12 years. After penile degloving, the dorsal groove on the penile shaft was absent. In two of the cadavers, multiple transverse cut-sections in the penile shaft showed that the two CCs were united into one single tubular structure that extended from the symphysis pubis to the glans penis. The cut section was kidney-shaped, with the corpus spongiosum lying under cover of the concave surface. No intercavernosal septum was identified. The transverse cut-section of the third cadaveric specimen revealed an incomplete fusion of the two CCs. An intercavernosal septum was present in its upper part, but absent in its lower part where the two CCs were fused together. In all three cadaveric specimens, the CCs showed a normal histologic pattern and the corpus spongiosum was morphologically normal. Based on biomechanical principles, we theorize that the blood volume occupying the two CCs would be greater, the penile rigidity stronger, and the penetration force more powerful in the two separate CCs as normal than in the two CCs if fused. However, further studies involving large number of cases are needed.

Role of androgen in prostate growth and regression: Stromal-epithelial interaction

The prostate is a secretory gland in which secretions produced by its cells are transported through the ductal system and discharged into the urethra. Each prostatic ductal system can be traced from the opening in the urethra as a single tubular structure from which branches and sub-branches are formed in a manner like the branching pattern of a tree. Owing to the distance from the urethral orifice, regions of the prostatic ductal system can be classed into the proximal, intermediate, and distal regions. In the distal region, the tips of the ductal system (equivalent to the top of the tree), the epithelial cells are tall and columnar in shape, and active in cell division. Cells of the intermediate region (equivalent to the majority of the body of the tree) are also of tall and columnar type but are mitotically quiescent. Cells in this region are the only ones that have the ability to secrete. Cell death is not evident in these two regions. Cells in the proximal region, a region that is immediately adjacent to the urethra (equivalent to the tree trunk) are low cuboidal or flat in shape and are actively undergoing cell death. These observations indicate that cells in different regions of the prostatic ductal system are not the same, even though they are exposed to the same circulating level of androgen. The recognition of this regional heterogeneity in cell shape and activity in the ductal system has advanced our understanding of the basic biology of the prostate. For example, our understanding of the cellular mechanism of action of androgen in the prostate should be re-evaluated. In the past, the convention concept of androgen action has been a stimulatory one, and a depletion of this androgenic support leads to prostatic cell death. The recognition of a regional heterogeneity in cellular activity has created a situation in which all prostatic cells in the same prostatic ductal system are exposed to the same level of circulating androgen. However, these cells are not responding to the same amount of androgen in the same manner: some are multiplying while others are dying. These observations indicate that the effect of androgen vary according to the location of prostatic cells in the ductal system. A new concept of the role of androgen in prostatic growth, differentiation, and cell death is discussed.

The ultrastructure of the tubular complex in the cytoplasm of cytolytic T lymphocytes.

The DNA synthesis, the cytolytic activity, and the ultrastructure of cytolytic T lymphocytes (CTL) derived from mixed mouse thymocyte culture on day 5 were studied. CTL of thymic origin were absorbed by centrifugation on the surface of target cell (TC) monolayers. At different time intervals after absorption, single tubular structures (TS) and complex of tubular structures (CTS) linked with ergastoplasmic reticulum, secretory granules, Golgi apparatus, coated vesicles, and multivesicular bodies were detected in the CTL cytoplasm. The linkage of CTS with ergastoplasmic reticulum, ribosomes, and secretory lymphocyte mechanism suggests the possibility of a secretory-receptor mechanism of TC cytolysis. The release of numerous secretory vacuoles was accompanied by the enlargement of the cytoplasmatic lymphocyte membrane surface, which seemed to cause its shedding. 'Membranosomas' were observed on CTL membrane; their role is still obscure and awaits further study.

Fine structure of the motile cells and flagella in a member of the Actinoplanaceae (Actinomycetales).

The motile cells (sporangiospores) of an undescribed member of the Actinoplanaceae are studied by electron microscopy as shadowed, negatively stained, and sectioned preparations. The rod-shaped spores exhibit a typically bacterial internal structure. However, a single tubular structure (rhapidosome) is positioned just inside the site of flagellar attachment of each spore and is oriented perpendicular to the direction of the flagella. Flagella arise from basal dises and pass through the plasma membrane and the two-layered cell wall to become associated with other flagella to function as a posteriorly directed unit. Each flagellum consists of a helical band or ribbon which dissociates into 5 or 6 subfibrils.