scholarly journals Secretion of a cytoplasmic lectin from Xenopus laevis skin.

1986 ◽  
Vol 102 (2) ◽  
pp. 492-499 ◽  
Author(s):  
N C Bols ◽  
M M Roberson ◽  
P L Haywood-Reid ◽  
R F Cerra ◽  
S H Barondes
Keyword(s):  
Electron Microscope ◽  
Xenopus Laevis ◽  
Mucous Gland ◽  
Gland Cells ◽  
Binding Lectin

The skin of Xenopus laevis contains a soluble beta-galactoside-binding lectin with a approximately 16,000-mol-wt subunit. It resembles similar lectins purified from a variety of tissues from other vertebrates, and differs from two other soluble X. laevis lectins from oocytes and serum that bind alpha-galactosides. The skin lectin is concentrated in the cytoplasm of granular gland and mucous gland cells, as demonstrated by immunohistochemistry with the electron microscope. Upon injection with epinephrine, there is massive secretion of the cytoplasmic lectin from the granular gland cells.

Mucous Gland Cells of the Outer Mantle Epithelium of Arca noae

Nature ◽  
1957 ◽  
Vol 180 (4600) ◽  
pp. 1492-1492 ◽  
Author(s):  
E. R. TRUEMAN
Keyword(s):  
Mucous Gland ◽  
Gland Cells ◽  
Outer Mantle Epithelium

An ultrastructural study of the effects of wheat germ agglutinin (WGA) on cell cortex organization during the first cleavage of Xenopus laevis eggs. II. Cortical wound healing

1979 ◽  
Vol 37 (1) ◽  
pp. 59-67
Author(s):  
M. Geuskens ◽  
R. Tencer
Keyword(s):  
Wound Healing ◽  
Plasma Membrane ◽  
Electron Microscope ◽  
Xenopus Laevis ◽  
Ultrastructural Study ◽  
Wheat Germ Agglutinin ◽  
Wheat Germ ◽  
Cell Cortex ◽  
Animal Pole ◽  
Annular Zone

Uncleaved fertilized eggs of Xenopus laevis treated with wheat germ agglutinin (WGA) have been pricked at the animal pole both inside and outside the regressed furrow region. The wounded cortex of both regions has been studied with the electron microscope and compared with the same region of wounded, untreated eggs. In all 3 cases, filaments are organized in an annular zone in the damaged cortex. When the surface is pricked outside the regressed furrow of WGA-treated embryos, bundles of microfilaments radiate from the ring and extend in deep folds which form a ‘star’ around the wound at the surface of the embryo. However, when the surface is pricked in the new membrane of the regressed furrow, filaments are intermingled with internalized portions of the plasma membrane. It is suggested that, when the surface is pricked outside the furrow region, more filaments are mobilized to counteract the tangential retraction of the membrane which has acquired more rigidity after WGA binding.

An Ultrastructural and Radioautographic Study of Early Oogenesis in the Toad Xenopus Laevis

1973 ◽  
Vol 12 (1) ◽  
pp. 71-93
Author(s):  
LESLEY WATSON COGGINS
Keyword(s):  
Electron Microscope ◽  
Xenopus Laevis ◽  
Thymidine Incorporation ◽  
Ultrastructural Level ◽  
Extrachromosomal Dna ◽  
Late Pachytene ◽  
Synaptonemal Complexes ◽  
Round Nucleus ◽  
A Cell ◽  
Major Period

Early oogenesis in the toad Xenopus laevis has been investigated at the ultrastructural level, with particular reference to the formation of extrachromosomal DNA. Thymidine incorporation was localized by electron microscope radioautography. In oogonia, the nucleus is irregular in outline and may contain several nucleoli. Oocytes, from premeiotic interphase to late pachytene, are found in cell nests which are estimated to consist of about 16 cells each. Adjacent oocytes within a nest are connected by intercellular bridges and develop synchronously. Each premeiotic interphase-leptotene oocyte has a round nucleus which contains one or two centrally located, spherical nucleoli. Electron-microscope radioautography showed that all nuclei in a cell nest incorporate thymidine synchronously during premeiotic S-phase. In zygotene oocytes, axial cores and synaptonemal complexes are observed in the nucleus and abut against the inner nuclear membrane in the region nearest the centre of the cell nest. The nucleolus is still more-or-less round in outline, but is asymmetrically positioned in the nucleus. It lies near the nuclear envelope on the side of the nucleus furthest away from the attachment of the chromosome ends, that is, nearest the outside of the cell nest. Each nucleolus is surrounded by a fibrillar ‘halo’ of nucleolus-associated chromatin into which a low level of thymidine incorporation occurs during zygotene. This is thought to represent the start of the major period of amplification of the ribosomal DNA. Pachytene is characterized by the presence of synaptonemal complexes in the nucleus. The nucleolus becomes very irregular in outline. The fibrillar area around it, which represents the extrachromosomal DNA, increases in size and thymidine is incorporated over the whole of this region. In late pachytene, many small fibrogranular bodies, the multiple nucleoli, are formed in it. The members of a cell nest become separated from one another at this time and begin to develop asynchronously. In diplotene, synaptonemal complexes are no longer observed in the nucleus. The most prominent structures in the nucleus are now the multiple nucleoli, which increase greatly in number in early diplotene. A large increase in cytoplasmic volume occurs and the oocyte grows in size.

Development of the Xenopus laevis hatching gland and its relationship to surface ectoderm patterning

Development ◽  
1991 ◽  
Vol 111 (2) ◽  
pp. 469-478 ◽  
Author(s):  
T.A. Drysdale ◽  
R.P. Elinson
Keyword(s):  
Retinoic Acid ◽  
Tyrosine Hydroxylase ◽  
Xenopus Laevis ◽  
Ciliated Cells ◽  
Surface Ectoderm ◽  
Gland Cells ◽  
The Face ◽  
Underlying Mechanisms ◽  
Development Proceeds ◽  
Hatching Gland

An antibody that recognizes tyrosine hydroxylase can be used as a marker for hatching gland cells in Xenopus embryos. Using this marker, we have shown that hatching gland cells are induced at the end of gastrulation and that presumptive hatching gland cells are localized to the anterior neural folds in Xenopus. The movements of neurulation bring the hatching gland cells together to form a characteristic Y pattern on the dorsoanterior surface of the head. The Y pattern delineates several zones of surface ectoderm which can be visualized by the presence or absence of ciliated cells. As development proceeds the hatching gland pattern is altered, demonstrating the active changes involved in forming the face. Lithium, UV irradiation and retinoic acid can be used to alter the hatching gland pattern in specific ways which help to understand the underlying mechanisms of ectodermal patterning.

Production and fate of erythroid cells in anaemic Xenopus laevis

1979 ◽  
Vol 35 (1) ◽  
pp. 403-415
Author(s):  
N. Chegini ◽  
V. Aleporou ◽  
G. Bell ◽  
V.A. Hilder ◽  
N. Maclean
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Xenopus Laevis ◽  
Red Blood Cells ◽  
Blood Cells ◽  
Complete Recovery ◽  
Cell Counting ◽  
Erythroid Cells ◽  
Spleen Cells ◽  
Sudden Release

Adult Xenopus laevis, rendered anaemic by phenylhydrazine injection, have been studied during the recovery from such anaemia. Electron microscopy of liver and spleen sections indicates that both of these organs are active in the phagocytosis and destruction of the old damaged red blood cells. May-Grunwald and Giemsa staining of liver and spleen cells following anaemia has been used to show that erythropoiesis also occurs in both liver and spleen, and this has been confirmed by electron-microscope studies of these organs. Cell counting and radiolabelling of the new population of circulating erythroid cells in the period following phenylhydrazine injection suggests that a sudden release of basophilic erythroblasts from liver and spleen is followed by mitosis of this new cell population in circulation, and that no further release of erythroid cells from these organs is likely until complete recovery has occurred.

Observations on the Structure of Hydra as seen with the Electron and Light Microscopes

1957 ◽  
Vol s3-98 (43) ◽  
pp. 315-326
Author(s):  
ARTHUR HESS ◽  
A. I. COHEN ◽  
ELAINE A. ROBSON
Keyword(s):  
Electron Microscope ◽  
Longitudinal Muscle ◽  
Homogeneous Layer ◽  
Muscle Fibres ◽  
Digestive Cells ◽  
Characteristic Appearance ◽  
Dense Granules ◽  
Gland Cells ◽  
Cytoplasmic Continuity ◽  
Transverse Muscle

Sections of hydra studied with the electron microscope show various structures which have been identified by referring to control histological sections and to previous descriptions. Certain features have also been examined in frozen-dried sections under the light microscope. In the ectoderm, epithelio-muscular cells contain various organelles, and also smooth longitudinal muscle-fibres with which mitochondria may be associated. The so-called ‘supporting fibres’ appear to be thin bundles of muscle-fibres. Although points of contact exist between muscle-fibres, there appears to be no cytoplasmic continuity. The muscle-fibres insert on the mesogloea, and appear to be separated from it by two membranes, one belonging to the cytoplasm surrounding the musclefibreand the other to the mesogloea. The mesogloea is extracellular and quite distinct from the intracellular muscle-fibres. It appears granular and sometimes presents an indistinct fibrous background. In frozen-dried material the mesogloea stains blue with Mallory's method, while the muscle-fibres stain red. Two main types of cells are found in the endoderm. Among these, some of the digestive cells contain transverse muscle-fibres, but they are less distinct than the longitudinal ectodermal fibres. Otherwise the digestive cells vary much in structure, but generally they contain vacuoles and their free surface is thrown into villi covered with small granules. The ‘foamy gland cells’ are filled with much larger vacuoles containing granular material. The vacuoles are discharged together with portions of cytoplasm, and at this stage lamellated double membranes and mitochrondria appear between the vacuoles. Both types of cell possess two flagella, which show a typical ultrastructure and are surrounded by a thick membrane. Various other cells of the ectoderm are distinguished by their characteristic appearance. Cnidoblasts, for instance, have been found to contain an extensive system of intercommunicating vacuoles bounded by membranes, and do not resemble the interstitial cells. In unexploded penetrant nematocysts the tube is preformed and the butt nd stylets can also be seen. The special gland-cells of the pedal disk show large, lectron-dense granules which are extruded from the cell without any cytoplasm. A relatively thick homogeneous layer on the surface of the pedal disk is distinguished by the electron microscope.

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