Search results for "Styela"
showing 10 items of 20 documents
Effetti antiproliferativi degli estratti di emociti dell'ascidia Styela plicata ( Tunicata)
2009
Cellular components and tunic architecture of the solitary ascidian Styela canopus (Stolidobranchiata, Styelidae).
1998
Abstract Cell distribution and tunic morphology in the ascidian Styela canopus were examined by electron microscopy. The observations showed that the outer covering is composed of a thin sinuous cuticle with several protrusions and a deep layer of ground substance. The fibrous component and its arrangement in the tunic were demonstrated: elementary fibrils exhibit a ‘microtubular’ structure and an elliptical cross-sectional shape. Four types of cells were described: clear vesicular tunic granulocytes, tunic microgranulocytes, unilocular tunic granulocytes, and globular tunic granulocytes. Morphofunctional aspects of the tunic tissue and certain phylogenetic relationships are discussed.
Circulating hemocytes and pharyngeal explants of Styela clava release hemagglutinin in vitro
1997
Tunicate blood cells are a mixed population, thus experiments that assay their immunodefense responses, such as release of hemagglutinins, were done to isolate different functional hemocytic types. Two sources of hemocytes from Styela clava were used, the hemolymph and the pharynx (the hemopoietic organ). Hemolymph centrifuged through a discontinuous Percoll gradient yielded four distinct bands of hemocytes. After incubation at 15°C, circulating hemocytes and those from pharyngeal cultures released hemagglutinin after 2 and 30 days. Highest titers were found in B1 (hyaline and compartment cells), B3 (hyaline cells and eosinophil granulocytes), and B4 (hyaline cells and debris). Hemagglutina…
Microscopic features of the tunic in young Styela canopus (Tunicata, Styelidae)
The tunic is a unique tissue in metazoans covering the epidermis of ascidians and other tunicates. The tunic is a multifunctional tissue that provides support, mechanical rigidity, and protection against infection and predation. The outermost surface of it is covered by a thin continuous layer called tunic cuticle. The tunic cuticle density and integrity must be maintained during the growth of the animal after metamorphosis, as it represents the primary body surface barrier preventing the mechanical damage. Using transmission electronic microscopy we attempted to characterize the cuticle morphology of young Styela canopus, a solitary ascidian (Styelidae), in comparison with the cuticle arch…
Immunological Activity of Ascidian Hemocytes
2001
In ascidians, various hemocyte types and their differentiation stages may be responsible for several immune functions. A central role in the immune effector mechanisms can be assigned to PO-containing hemocytes and prophenoloxidase system. Morula cell in Styela plicata and univacuolar refringent granulocyte in Ciona intestinalis, a probable intermediate stages in the differentiation pathway of morula cell, may be cytotoxic cells. They are involved in immune reactions of solitary and colonial ascidians. We have shown that they are provided with a PO-linked spontaneous cytotoxic activity and recognize mammalian erythrocytes or tumor cells markers. The toxic molecules can be radical oxygen int…
Effects of tributyltin(IV) chloride on fertilization ofStyela plicata(Ascidiacea: Tunicata): II. Scanning and transmission electron microscopy studies
2003
The morphological aspects of Styela plicata fertilization after treatment with tributyltin(IV) chloride are described by means of scanning and transmission electron microscopy investigations. Alterations have been shown both on female and male gametes; spermatozoa, all the egg envelopes and the mitochondria of the egg cortical cytoplasm are modified in relation to incubation time. As a consequence, the damage to gametes blocks sperm–egg interaction and fertilization does not occur. Copyright © 2003 John Wiley & Sons, Ltd.
Follicle Cells of Styela plicata Eggs (Ascidiacea)
2001
Styela plicata eggs are surrounded by large follicle cells that at LM appear as highly vacuolated and columnar in shape; at the apical end of each cell lies a very large and clear vacuole, half of which extends inward. Electron microscope observations show a Single layer of largely spaced box-like follicle cells; the close cell-cell contact at their base is realized by interdigitations. The cell surface shows a peculiar structure, more developed in the latero-basal regions, consisting of a complex of membrane extensions, i.e. microvilli, filopodia and lamellipodia. Filopodia irradiate in all directions towards the adjacent cells and the outermost vitelline coat, thus creating a complex netw…
The Follicle Cells of Styela Plicata (Ascidiacea, Tunicata): A Sem Study
2000
The morphological aspect of the follicle cells of Styela plicata eggs is described by means of scanning electron microscope investigations. The follicular layer is made of spaced, cylindrical box-like cells which are arranged hexagonally. They adhere to the egg through a complex network of membrane extensions making an overall thin layer on the vitelline coat. The walls of the follicle cells are plentifully provided with microvilli, filopodia and lamellipodia, which allow a connection among the cells. At their apical end lies a large vacuole containing a granule, probably involved in secretion. At insemination the majority of spermatozoa is distributed on the apical membrane of the follicle…
The identification and localization of two intermediate filament proteins in the tunic of Styela plicata (Tunicata, Styelidae).
2009
The intermediate filament (IF) proteins Styela C and Styela D from the tunicate Styela (Urochordata) are co-expressed in all epidermal cells and they are thought to behave as type I and type II keratins. These two IF proteins, Styela C and Styela D, were identified in immunoblots of proteins isolated from the tunic of Styela plicata. The occurrence and distribution of these proteins within the tunic of this ascidian was examined by means of immunofluorescence and immunoperoxidase techniques, using anti-Styela C and anti-Styela D antibodies. In addition, immuno-electron microscopy of the tunic showed that the two proteins are located in the cuticle layer and in the tunic matrix. These result…