Single Layer Of Squamous Cells Research Articles

Cystic hygroma in a female suckling pig: a case report

BackgroundCystic hygromas (lymphangiomas) are rarely reported in various animal species, humans included. A hygroma is a benign congenital malformation of the lymphatic drainage system, presenting itself as a mass consisting of multiple cysts of various sizes with a watery content.Case presentationThis report describes clinical, ultrasonographic, and post-mortem findings of a cystic hygroma in a suckling pig. The mass was characterized by a few thin-walled cysts, containing clear yellow serous fluid. Histologically, the central cavity was lined by a single layer of squamous cells, supported by a thick fibrous stroma. On immunohistochemistry, scattered lining cells were weakly positive for Factor-VIII, suggesting their possible endothelial origin.ConclusionsThis case report contributes to raising awareness on this condition in pigs allowing early identification in life so that appropriate care can be provided. The case report attributes to science on hygromas in general, as better understanding of pathologic features, the aetiology and appropriate treatment are needed.

Endothelial Mechanosensors for Atheroprone and Atheroprotective Shear Stress Signals.

Vascular endothelial cells (ECs), derived from the mesoderm, form a single layer of squamous cells that covers the inner surface of blood vessels. In addition to being regulated by chemical signals from the extracellular matrix (ECM) and blood, ECs are directly confronted to complex hemodynamic environment. These physical inputs are translated into biochemical signals, dictating multiple aspects of cell behaviour and destination, including growth, differentiation, migration, adhesion, death and survival. Mechanosensors are initial responders to changes in mechanical environments, and the overwhelming majority of them are located on the plasma membrane. Physical forces affect plasma membrane fluidity and change of protein complexes on plasma membrane, accompanied by altering intercellular connections, cell-ECM adhesion, deformation of the cytoskeleton, and consequently, transcriptional responses in shaping specific phenotypes. Among the diverse forces exerted on ECs, shear stress (SS), defined as tangential friction force exerted by blood flow, has been extensively studied, from mechanosensing to mechanotransduction, as well as corresponding phenotypes. However, the precise mechanosensors and signalling pathways that determine atheroprone and atheroprotective phenotypes of arteries remain unclear. Moreover, it is worth to mention that some established mechanosensors of atheroprotective SS, endothelial glycocalyx, for example, might be dismantled by atheroprone SS. Therefore, we provide an overview of the current knowledge on mechanosensors in ECs for SS signals. We emphasize how these ECs coordinate or differentially participate in phenotype regulation induced by atheroprone and atheroprotective SS.

Oogenesis: From Oogonia to Ovulation in the Flagfish, Jordanella floridae Goode and Bean, 1879 (Teleostei:Cyprinodontidae).

We provide histological details of the development of oocytes in the cyprinodontid flagfish, Jordanella floridae. There are six stages of oogenesis: Oogonial proliferation, chromatin nucleolus, primary growth (previtellogenesis [PG]), secondary growth (vitellogenesis), oocyte maturation and ovulation. The ovarian lamellae are lined by a germinal epithelium composed of epithelial cells and scattered oogonia. During primary growth, the development of cortical alveoli and oil droplets, are initiated simultaneously. During secondary growth, yolk globules coalesce into a fluid mass. The full-grown oocyte contains a large globule of fluid yolk. The germinal vesicle is at the animal pole, and the cortical alveoli and oil droplets are located at the periphery. The disposition of oil droplets at the vegetal pole of the germinal vesicle during late secondary growth stage is a unique characteristic. The follicular cell layer is composed initially of a single layer of squamous cells during early PG which become columnar during early vitellogenesis. During primary and secondary growth stages, filaments develop among the follicular cells and also around the micropyle. The filaments are seen extending from the zona pellucida after ovulation. During ovulation, a space is evident between the oocyte and the zona pellucida. Asynchronous spawning activity is confirmed by the observation that, after ovulation, the ovarian lamellae contain follicles in both primary and secondary growth stages; in contrast, when the seasonal activity of oogenesis and spawning ends, after ovulation, the ovarian lamellae contain only follicles in the primary growth stage. J. Morphol. 277:1339-1354, 2016. © 2016 Wiley Periodicals, Inc.

Oogenesis of microlecithal oocytes in the viviparous teleost Heterandria formosa

Viviparous teleosts exhibit two patterns of embryonic nutrition: lecithotrophy (when nutrients are derived from yolk that is deposited in the oocyte during oogenesis) and matrotrophy (when nutrients are derived from the maternal blood stream during gestation). Nutrients contained in oocytes of matrotrophic species are not sufficient to support embryonic development until term. The smallest oocytes formed among the viviparous poeciliid fish occur in the least killifish, Heterandria formosa, these having diameters of only 400 μm. Accordingly, H. formosa presents the highest level of matrotrophy among poeciliids. This study provides histological details occurring during development of its microlecithal oocytes. Five stages occur during oogenesis: oogonial proliferation, chromatin nucleolus, primary growth (previtellogenesis), secondary growth (vitellogenesis), and oocyte maturation. H. formosa, as in all viviparous poeciliids, has intrafollicular fertilization and gestation. Therefore, there is no ovulation stage. The full-grown oocyte of H. formosa contains a large oil globule, which occupies most of the cell volume. The oocyte periphery contains the germinal vesicle, and ooplasm that includes cortical alveoli, small oil droplets and only a few yolk globules. The follicular cell layer is initially composed of a single layer of squamous cells during early previtellogenesis, but these become columnar during early vitellogenesis. They are pseudostratified during late vitellogenesis and reduce their height becoming almost squamous in full-grown oocytes. The microlecithal oocytes of H. formosa represent an extreme in fish oogenesis typified by scarce yolk deposition, a characteristic directly related to matrotrophy.

Gestational morphogenesis of the uterine epithelium of the gummy shark (Mustelus antarcticus)

Developing embryos of the non-placental, viviparous gummy shark (Mustelus antarcticus) are supplied with yolk from external and internal yolk sacs throughout the initial stages of gestation. Yolk supplies are exhausted by the 7th month of an 11-12 month gestation. During embryonic development, there is an approximate 800% gain in dry mass. These factors suggest nutrients are transferred from the mother to the young. The results of the present study provide some insights into how this is occurring. The uteri are paired and both are functional. Using both light and transmission electron microscopy, regions of the uterus were examined throughout maturation and gestation. The layers of the uterine wall throughout the entire length are similar to the uteri of other chondrichthyans previously examined. The uterine epithelium of the body of the uterus is smooth contoured, does not form villi, and undergoes cyclical and secretory changes throughout maturity and gestation. In immature uteri, the epithelium is simple columnar with minimal periodic acid-Schiff-positive and Alcian blue-positive secretory vesicles. In mature uteri, the epithelium is highly stratified with cuboidal cells containing numerous Alcian blue-positive and periodic acid-Schiff-positive vesicles. With pregnancy, prominent changes include a reduction in the number of cell layers, a reduction in cell size, a reduction in the connective tissue intervening between epithelium and blood vessel endothelium, and an increase in blood vessel number and size, so that at term, the uterine compartment consists of a single layer of squamous cells immediately underlain by sinusoidal-like blood vessels. These features along with a small number of secretory vesicles, dilated intercellular spaces, and clear transport vesicles suggest the transepithelial transfer of water and minerals from the maternal to embryonic environment, supplemented by minimal uterine secretions. This is defined as minimal histotrophy and this article represents the first detailed description of this reproductive mode.

Oogenesis in the viviparous matrotrophic lizard Mabuya brachypoda

Oogenesis in the lizard Mabuya brachypoda is seasonal, with oogenesis initiated during May-June and ovulation occurring during July-August. This species ovulates an egg that is microlecithal, having very small yolk stores. The preovulatory oocyte attains a maximum diameter of 0.9-1.3 mm. Two elongated germinal beds, formed by germinal epithelia containing oogonia, early oocytes, and somatic cells, are found on the dorsal surface of each ovary. Although microlecithal eggs are ovulated in this species, oogenesis is characterized by both previtellogenic and vitellogenic stages. During early previtellogenesis, the nucleus of the oocyte contains lampbrush chromosomes, whereas the ooplasm stains lightly with a perinuclear yolk nucleus. During late previtellogenesis the ooplasm displays basophilic staining with fine granular material composed of irregularly distributed bundles of thin fibers. A well-defined zona pellucida is also observed. The granulosa, initially composed of a single layer of squamous cells during early previtellogenesis, becomes multilayered and polymorphic. As with other squamate reptiles, the granulosa at this stage is formed by three cell types: small, intermediate, and large or pyriform cells. As vitellogenesis progresses the oocyte displays abundant vacuoles and small, but scarce, yolk platelets at the periphery of the oocyte. The zona pellucida attains its maximum thickness during late oogenesis, a period when the granulosa is again reduced to a single layer of squamous cells. The vitellogenic process observed in M. brachypoda corresponds with the earliest vitellogenic stages seen in other viviparous lizard species with larger oocytes. The various species of the genus Mabuya provided us with important models to understand a major transition in the evolution of viviparity, the development of a microlecithal egg.

Differential expression of a WD protein during squamous differentiation of tracheal epithelial cells.

The lining of the trachea consists of a pseudostratified, mucociliary epithelium that under a variety of conditions, such as vitamin A deficiency, toxic and mechanical injury, becomes a stratified squamous epithelium. Several in vitro cell culture models have been established to study the process of differentiation of airway epithelium. Such studies have indicated that mucosecretory differentiation of tracheal epithelial cells can be modulated by substratum. This study was undertaken to understand molecular mechanisms of squamous differentiation in tracheal epithelia. Primary cultured tracheal cells grown on uncoated filters were differentiated to single layer of squamous cells, whereas cells were grown as stratified columnar cells on collagen-I coated filters. The responses to secretagogues were altered according to culture conditions. DD-PCR revealed that FAK and a WD protein expression was increased in squamous tracheal epithelia. Expression of a WD protein was changed by the treatment of retinoic acid in various epithelial cells. These results indicated that squamous differentiation of tracheal cells changes the expression of a variety of genes, and that the experimental model for this study can be employed to study molecular mechanisms of squamous differentiation in airway epithelial cells.

Spheroid Formation of Bovine Endometrial Stromal Cells with Non-Adherent Culture Plate.

A multicellular mass (spheroid) was developed from bovine endometrial stromal cells with non-adherent culture plates. Cells cultured in a spheroid-plate® were spontaneously aggregated and formed a cell mass rough in appearance 24 h after the start of culture. After 3 days of culture, the cell mass became oval-shaped in the range 375 to 900 μm in diameter. The size of the spheroid depended on the number of cells plated in each well. Histological examination indicated that each spheroid was covered with a single layer of squamous cells, and cuboidal cells occupied the inside of the spheroid. The size of the spheroid decreased gradually and the inner cells of the spheroid became sparse and irregular in size after culture for more than 7 days. ProMMP-2 mRNA was found both in monolayer culture cells and the spheroid, but the active form of MMP-2 protein was found only in the condition medium of the spheroid. The present study demonstrated that the spheroid was easily generated from bovine endometrial stromal cells by using a non-adherent plate. Expression of the active form MMP-2 indicates that the cells in the spheroid changed their character not only morphologically but also functionally. These results indicate that the spheroid developed by the present method could provide a new tool for analyzing the functions of bovine endometrium.

A CASE OF EPIDERMOID CYST OF THE SPLEEN PRESENTED WITH A SOLITARY SPLENIC ABSCESS

Epidermoid cysts of the spleen are relatively rare, and most of them are found incidentally as an asymp-tomatic mass in the left upper quadrant. In this paper, an extremely rare case of epidermoid cyst of the spleen presented with a solitary splenic abscess is reported. A 26-year-old woman without previous medical history was admitted to the hospital because of high fever and left hypochondric pain. A infant'head-sized, elastic soft tumor was palpated in the upper quadrant. White blood cell count was 10, 700/mm and CRP was 15.0mg/dl. Computed tomography and ultranonography demonstrated a huge cystic mass in the left subphrenic space. The serum CA 19-9 levels were as high an 97U/ml and 122U/ml, respectively. Echo-guided needle aspiration of the cyst yielded a fluid that was positive for Staphylococcus aureus and the levels of CEA, CA 19-9, 194 CA 125 were extremely high, 76ng/ml, 20, 705U/ml, and 29, 400U/ml, respectively. Partial splenectomy was per-formed. Histologically, the inside of the cyst wall was mostly comprised of infiltrating cells and was partly cov-ered with a single layer of squamous cells. It was diagnosed as an epidermoid cyst of the spleen accompanied with splenic abscess. The postoperative course was uneventful.

Developmental changes of the oocyte and its enveloping layers, inmicropercops swinhonis(Pisces: Perciformes)

In the goby Micropercops swinhonis, the development of its egg's enveloping layers could be divided into 4 stages. In the earliest developmental period, stage I, there is a simple oocyte surrounded by a layer of squamous follicular cells. Stage II corresponds to the yolk vesicle stage of vitellogenesis. Here the initial follicular layer has become bilaminar with the retention of its outer squamous cell layer and the acquisition of an inner cuboidal cell layer just over the zona radiata. The number and size of the cuboidal cells increases throughout this stage. Stage III corresponds to the yolk granule stage of true vitellogenesis. Here the cuboidal cells begin to be replaced by columnar cells. As the oocyte grows, the columnar cells increase in size. The columnar cells produce cytoplasmic neutral mucins and by the end of this stage their cytoplasm has been filled with this mucin. In stage IV a single layer of squamous cells still remained as the outer follicular layer of the oocyte. The secretory activity...

The ultrastructure of the Schistosoma mansoni egg.

Helminth eggs have resisted analysis by electron microscopy because fixatives, dehydrating agents, and embedding media penetrate these eggs poorly. Slam-freezing at liquid nitrogen temperature followed by freeze-substitution and Spurr's medium embedment provides preservation of the internal structure of the Schistosoma mansoni egg shell, developing miracidium, and perimiracidial structures. The egg shell consists of the three previously described layers (outer microspinous, middle intermediately dense, and inner dense layers) with cribriform pores. A newly described layer (Reynolds' layer) develops subjacent the egg shell and is comprised of densely-packed branching filaments. A single layer of squamous cells (von Lichtenberg's envelope) closely adheres to Reynolds' layer. Between von Lichtenberg's envelope and the embryo is a space (Lehman's lacuna); this space is initially filled with electron-lucent fluid, but subsequently masses of granulofloccular material (Cheever bodies) develop; Cheever bodies are partially membrane bound. Epidermal plates differentiate from superficial cells of the embryonal cell mass, while epidermal ridges differentiate from cells just below the surface of the embryonal cell mass. The cytoplasmic layer (von Lichtenberg's envelope) interposed between the host extracellular fluid and the developing miracidia effect a barrier against a simple passive diffusion; this infers that complex macromolecules, such as schistosomal egg antigen, undergo active, and perhaps selective, transport in or out of the egg.

The allantois of the North American opossum (Didelphis virginiana) with preliminary observations on the yolk sac endoderm and trophectoderm.

During the middle of prenatal day 10, the opossum allantois forms as a ventral outgrowth of the hindgut. By day 11 it appears as a large, fluid filled sac and by the middle of day 12 (just prior to birth) it reaches its maximal development. The simple squamous epithelium lining the allantois consists of only one cell type that often contains numerous filaments in the apical cytoplasm. At the luminal surface, the apices of the cells are united by junctional complexes and desmosomes are present between adjacent cells. The luminal surface is irregular, whereas laterally and basally the cell membranes show few if any infoldings. Mitotic figures and presumptive degenerating cells occasionally occur in the allantoic epithelium which rests on a delicate basal lamina. The allantois is covered by a simple squamous mesothelium that lacks a distinct basal lamina. Between the two epithelial sheets lie mesenchymal cells, collagen fibers, and blood vessels. No specializations of cell membranes were noted in either of the epithelial layers. The yolk sac endoderm consists of a single layer of squamous cells whose cytoplasm contains scattered profiles of rough endoplasmic reticulum and mitochondria. Extensive lateral and basal infoldings of the plasmalemma were not observed in these endodermal cells. The morphology of the trophectodermal (trophoblastic) cells indicates a cell type that is active in the transport of materials. Since the endodermal cells that line the allantois lack morphological features that would suggest the presence of mechanisms for transport or exchange, and because they remain relatively unchanged throughout pregnancy, it is thought that the allantois functions primarily in the storage of urinary wastes during prenatal life.(ABSTRACT TRUNCATED AT 250 WORDS)

The Fine Structure of the Oesophageal Diverticula in the Mosquito Aedes triseriatus1, 2

The fine structure of the oesophageal diverticula of Aedes triseriatus (Say) (Diptera: Culicidae) was studied in adults and pupae primarily by electron microscopy. Two small dorsal diverticula lie between the flight muscles; one large ventral diverticulum, or crop, lies in the abdomen. The walls of the diverticula consist of an inner noncellular cuticle, a thin epithelium, and an outer network of striated muscle fibers. The cuticular lining is resistant to potassium hydroxide treatment and is composed of 2 layers. A thin osmiophilic layer, the intima, lines the lumen, and a nondense material lies adjacent to the intima. The latter material is difficult to distinguish in the adult. The epithelium is a single layer of squamous cells with large nuclei; the cells in the adult do not appear metabolically active, but the epithelium in the pupa contains an abundant rough endoplasmic reticulum and numerous mitochondria. Large circular muscle fibers pass around the diverticula, and from them smaller fibers extend horizontally and longitudinally. Each fiber consists of a single myofibril which is composed of centrally located myosin filaments with the organelles along the periphery. The muscle nuclei may contain fine granules throughout or contain clumps of dense material. Two longitudinal nerves were found in a dorsal diverticulum. Each nerve was surrounded by a thick basement membrane and contained 4 axons; the axons were ensheathed in glial cells. In the oesophagus anterior to the diverticula, the intima has thickenings of dense material along its inner surface. The epithelium is vacuolated and is microvillate along the lumenal surface. Posteriorly in the oesophagus and in the ducts of the diverticula, the epithelium is flattened. The cuticle is composed of 3 layers; the intima lining the lumen, a layer which is less dense and is thickened to form spines, and a 3rd layer of nondense material which contains small, scattered fibers. The spines do not appear to have any sensory function. In the cardiac valve region, the epithelial cells are cuboidal and the cuticular lining terminates.

The Histopathology of Experimental Rhinitis in Pigs Produced by a Strain of Aujeszky’s Disease Virus

SUMMARY Seventy pigs aged between 4 days and 14 weeks were infected intranasally with Aujeszky’s disease virus and killed daily over a period of 16 days. A focal necrotising rhinitis developed by the second day, and persisted until the seventh day after infection. The lesions primarily affected the surface epithelium and upper mucosa but frequently the necrosis extended into the deeper structures including the nasal glands and, rarely, bone. These changes were accompanied by heavy infiltration of the mucosa by lymphocytes and macrophages. Healing began in some areas on the fifth day with the covering of the ulcerated mucosa by a single layer of squamous cells, which was rapidly converted to a stratified squamous epithelium. Rhinitis was also produced by infection of a further 21 pigs by exposure to an aerosol cloud of Aujeszky’s disease virus, but the lesions were neither as numerous nor as severe as those following the administration of intranasal drops.