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Dense Bodies (dense + body)
Selected AbstractsUltrastructure of spermatozoa of lizards in the genus Mabuya from Central BrazilACTA ZOOLOGICA, Issue 1 2009S. M. De Sá Mandel Abstract This is the first description of spermatozoal ultrastructure of Mabuya skinks. The spermatozoa of the species studied are filiform, consisting of a head region, a midpiece and a tail. The head is characterized by the following features: a depressed acrosome anteriorly, an acrosome vesicle divided into cortex and medulla, paracrystalline subacrosomal material, a pointed tip perforatorium, a circular perforatorium base plate inside the subacrosomal cone, an epinuclear lucent zone separated from the subacrosomal cone by a membrane, a large nuclear rostrum, and round nuclear shoulders. The midpiece presents a bilateral stratified laminar structure, a distal centriole, peripheral fibres 3 and 8 grossly enlarged, columnar mitochondria with linear cristae, dense body rings and a triangular annulus. Finally, the tail is composed of a principal piece and an end piece. An axoneme and a fibrous sheath characterize the principal piece, and the end piece is formed only by an axoneme, which loses its pattern in the last portion. Comparisons with members of Teiidae revealed differences in the numbers of dense rings. A well-developed epinuclear lucent zone in Mabuya is less prominent among teiids. In the spermatozoa of Mabuya, the first ring of dense bodies is very large, uniquely resembling the condition present in snakes. [source] Microscopic structure of the sperm storage tubules in the polygynandrous alpine accentor, Prunella collaris (Aves)ACTA ZOOLOGICA, Issue 4 2001Akira Chiba Abstract We describe the microscopic structure of the sperm storage tubules (SSTs) of the polygynandrous alpine accentor, Prunella collaris. The SSTs were found at the utero-vaginal junction of the oviduct and were composed of a single layer of columnar epithelium. The cells of the tubule proper were non-ciliated and had a round or oval nucleus in their basal portion. Their cytoplasm was finely or coarsely vacuolated due to lipid inclusions. Under the electron microscope, the epithelial cells exhibited a number of mitochondria, Golgi bodies, occasional lysosome-like dense bodies, granular endoplasmic reticula, junctional complex, and tonofilaments. The apical margin of the cells was fringed with numerous microvilli. The epithelial lining of the SSTs was devoid of mucous cells, but showed occasional infiltration of lymphoid cells. No contractile elements were found in association with the SSTs, but a close apposition of unmyelinated nerve fibres to the basal part of the SST cells was recognized. Intraluminal sperm were arranged in bundles, and their heads were orientated towards the distal portion of the SSTs. Evidence for engulfment of sperm by the SST cells was obtained for the first time. A sign of atrophy or regression of the SSTs was found in one specimen. [source] Ultrastructural clues for the potent therapeutic effect of melatonin on aging skin in pinealectomized ratsFUNDAMENTAL & CLINICAL PHARMACOLOGY, Issue 6 2006Mukaddes E Abstract Recently we have reported a significant reduction in the thickness of epidermis and epidermis + dermis in the back, abdominal and thoracic skin of the long-term pinealectomized rats and the potent therapeutic effect of melatonin on the pinealectomy-induced morphometric changes. The present study was aimed to determine the fine structure of the abdominal and thoracic skin in pinealectomized rats and the effect of melatonin on skin ultrastructure. Rats were pinealectomized or sham operated (control) for 6 months. Half of the pinealectomized rats were treated with 4 mg/kg melatonin during the last month of the experiment. Pinealectomy resulted in prominent ultrastructural changes in the skin. Epidermal atrophy, disorganization and cytological atypia were obvious. Tonofilament distribution was not uniform, and intercellular space was narrow. Nuclear irregularity and heterochromatin condensation were detected. Many mitochondria were irregular and edematous with increased translucence of the matrix, either partial or total destruction of crests and frequently the presence of vacuoles, myelin figures and dense bodies. Microprojections of basal cells into the dermis were observed. The dermis was thin, and collagenous fibers were loosely arranged. The epidermis in melatonin administered pinealectomized rats was obviously thicker than that of pinealectomized rats. The cells of each layers had characteristic morphological and ultrastructural features. Nuclear irregularity and heterochromatin condensation were not seen. Mitochondria were generally normal in ultrastructural appearance but rarely vacuoles and myelin figures were observed. The dermis was thick, and collagenous fibers were closely packaged. This paper provides an additional ultrastructural evidence that the damage to mitochondria is the major contributory factor to skin aging and that melatonin has potent therapeutic effects in reducing age-related changes via protecting fine structure of the skin. [source] Inflammatory cytokines induce the transformation of human dermal microvascular endothelial cells into myofibroblasts: a potential role in skin fibrogenesisJOURNAL OF CUTANEOUS PATHOLOGY, Issue 2 2007V. Chaudhuri Background:, The myofibroblast plays a central role in wound contraction and in the pathology of fibrosis. The origin(s) of this important cell type in skin has not been firmly established. Methods:, Human epithelioid dermal microvascular endothelial cells (HDMEC) were isolated from foreskin tissue and maintained in cell culture. The transformation of epithelioid HDMEC into myofibroblasts (EMT) was induced by the inflammatory cytokines interleukin-1, (IL-1,) or tumour necrosis factor-, (TNF-,), and the transformed cells were characterized by electron microscopy, immunohistochemistry and quantitative RT-PCR. Results:, After short-term exposure to IL-1, or TNF-, (<3 days), EMT was reversible; after long-term exposure (>10 days), EMT was permanent. The transformed cells were identified as myofibroblasts by cytoplasmic microfilaments with dense bodies and attachment plaques, by the expression of ,-smooth muscle actin, type I collagen and calponin, and by quantitative RT-PCR gene expression of type I collagen and ,-smooth muscle actin. Conclusions:, Long-term exposure to TNF-, or IL-1, induced the permanent transformation of HDMEC into myofibroblasts in cell culture. A similar transformation following chronic inflammatory stimulation in vivo may explain one source of myofibroblasts in skin fibrogenesis. [source] Ultrastructural aspects of the follicular cells of the pars tuberalis in bats related to the seasonal cycleTHE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 2 2003Giacomo Azzali Abstract The topography and structure of the follicular cells and the follicular cavity of the hypophyseal pars tuberalis (PT) were studied in adult hibernating bats (Pipistrellus pipistrellus and Rhinolophus ferrumequinum) of both sexes, during the annual seasonal cycle and the reproductive cycle. The follicular cells were found to be organized around a central cavity. They showed a polyhedral shape and apical microvilli protruding into central cavities. During hibernation, the follicular cells showed active cytoplasmic organelles, clusters of glycogen particles, and lipid droplets. In the supranuclear cytoplasm, 9+2 type cilia, some dense bodies, microvesicular vacuoles, and thin actin-like filaments (rather scarce during autumn) were detected. The contents of the follicular cavity showed well-defined ultrastructural seasonal characteristics, with a colloid-like aspect during awakening and a strongly granular aspect during autumn oestrus and mating. Positive staining for PAS and paraldehyde fuchsin, and a marked reaction to lectins PHA-L4, MAM, and RCA 60 suggested the presence of sialo-glycoproteins in the follicular cavities. Both follicular and endocrine PT-specific cells appeared to mark the boundary of follicular cavities. This finding suggests that the follicular cavity contents are comprised of both types of cells, rather than by cell fragmentation or degeneration products. Anat Rec Part A 273A:763,771, 2003. © 2003 Wiley-Liss, Inc. [source] Ultrastructural Studies of Henneguya rhamdia n. sp. (Myxozoa) a Parasite from the Amazon Teleost Fish, Rhamdia quelen (Pimelodidae)THE JOURNAL OF EUKARYOTIC MICROBIOLOGY, Issue 6 2005EDILSON MATOS Abstract. Henneguya rhamdia n. sp. is described in the gill filaments of the teleost fish Rhamdia quelen, collected from the Peixe Boi River, State of Pará, Brazil. This myxosporean produced spherical to ellipsoidal plasmodia, up to 300 ,m in diameter, which contained developmental stages, including spores. Several dense bodies up to 2 ,m in diameter were observed among the spores. The spore body was ellipsoidal (13.1 ,m in length, 5.2 ,m in width, and 2.5 ,m in thickness) and each of the two valves presented a tapering tail (36.9 ,m in length). These valves surrounded the binucleated sporoplasm cell and two equal ellipsoidal polar capsules (4.7 × 1.1 ,m), which contained 10,11 (rarely 12) polar filament coils. The sporoplasm contained sporoplasmosomes with a laterally eccentric dense structure with a half-crescent section. Based on the data obtained by electron microscopy and on the host specificity, the spores differed from previously described Henneguya species, mainly in their shape and size, number and arrangement of the polar filament coils, and sporoplasmosome morphology. [source] Identifying Putative Promoter Regions of Hermansky-Pudlak Syndrome Genes by Means of Phylogenetic FootprintingANNALS OF HUMAN GENETICS, Issue 4 2009Horia Stanescu Summary HPS is an autosomal recessive disorder characterized by oculocutaneous albinism and prolonged bleeding. Eight human genes are described resulting in the HPS subtypes 1,8. Certain HPS proteins combine to form Biogenesis of Lysosome-related Organelles Complexes (BLOCs), thought to function in the formation of intracellular vesicles such as melanosomes, platelet dense bodies, and lytic granules. Specifically, BLOC-2 contains the HPS3, HPS5 and HPS6 proteins. We used phylogenetic footprinting to identify conserved regions in the upstream sequences of HPS3, HPS5 and HPS6. These conserved regions were verified to have in vitro transcription activation activity using luciferase reporter assays. Transcription factor binding site analyses of the regions identified 52 putative sites shared by all three genes. When analysis was limited to the conserved footprints, seven binding sites were found shared among all three genes: Pax-5, AIRE, CACD, ZF5, Zic1, E2F and Churchill. The HPS3 conserved upstream region was sequenced in four patients with decreased fibroblast HPS3 RNA levels and only one HPS3 mutation in the coding exons and surrounding exon/intron boundaries; no mutation was found. These findings illustrate the power of phylogenetic footprinting for identifying potential regulatory regions in non-coding sequences and define the first putative promoter elements for any HPS genes. [source] | |||||||||||||