An immuno-fluorescent study of lens regeneration in larval Xenopus laevis

Development ◽  
1965 ◽  
Vol 13 (2) ◽  
pp. 171-179
Author(s):  
John C. Campbell
Keyword(s):  
Xenopus Laevis ◽  
Cell Layer ◽  
Morphological Changes ◽  
Posterior Wall ◽  
Corneal Tissue ◽  
Lens Regeneration ◽  
Small Clump

It is well known that several species of amphibia, especially those of the genus Triturus, can regenerate a lens after removal of the original lens from the eye. In most of these species the regenerate develops from the iris (Reyer, 1954), but in larval Xenopus laevis (Overton &Freeman, 1960; Freeman & Overton, 1961, 1962; Freeman, 1963; Campbell, 1963) and possibly in early embryonic stages of Hynobius unnangso (Ikeda, 1936, 1939) the regenerating lens can be formed from corneal tissue. The morphological changes associated with regeneration of the lens from the cornea in X. laevis have been fully described by Freeman (1963), who has shown that the regenerate develops from the inner cell layer of the outer, or ectodermal, cornea, appearing initially as a small clump of cells in the midpupillary region. This aggregate organizes into a vesicle, from the posterior wall of which the primary lens fibres are formed.

Lens regeneration from cornea of larval Xenopus laevis in the presence of the lens

Development ◽  
1978 ◽  
Vol 48 (1) ◽  
pp. 205-214
Author(s):  
Julie G. Reeve ◽  
Arthur E. Wild
Keyword(s):  
Xenopus Laevis ◽  
Histological Examination ◽  
Cell Layer ◽  
Stage Iv ◽  
Stage Iii ◽  
Posterior Chamber ◽  
Lens Regeneration ◽  
Lens Fibre

In Xenopus laevis tadpoles, wounding of the outer cornea failed to initiate lens regeneration. If both the outer and inner corneas were wounded or if the lens was dislocated, lens regeneration was initiated but failed to continue beyond stage III. However, lensectomy followed by re-implantation of the lens resulted in the regeneration of a fully differentiated lens in several cases, despite the presence of the re-implanted lens. Although some of the regenerates in these eyes were also arrested at stage III, those which attained full lens differentiation, i.e. stage V, developed normally and synthesized crystallins from the onsetof stage IV as indicated by a positive immunofluorescence reaction. Histological examination of the dislocated and re-implanted lenses showed the majority of them to be normal in appearance. Cornea transplanted to the posterior chamber of the eye also regenerated a lens in the presence of the re-implanted lens. All these regenerates underwent lens fibre differentiation to give stage-V regenerates. These findings show that lens regeneration from the cornea can occur in the presence of lens. Results are discussed on the basis that contrary to earlier suggestions, an inhibitory lens factor does not exist in vivo, but rather that a factor for the initiation and maintenance of regeneration emanates from the eye cup and upon wounding of the inner cornea is able to reach the inner cell layer of the outer cornea and initiate lens regeneration.

An Immunological Approach to the Problem of Lens Regeneration

Development ◽  
1959 ◽  
Vol 7 (4) ◽  
pp. 549-555
Author(s):  
J. Langman ◽  
B. D. Prescott
Keyword(s):  
Posterior Wall ◽  
Dorsal Part ◽  
Pigment Layer ◽  
Lens Regeneration ◽  
Immunological Approach

Lens regeneration from the dorsal rim of the iris has been observed after removal of the original lens in many species of the genus Triturus (Stone, 1952, 1954, 1958; Zalokar, 1944; Reyer, 1954). Transformation of the iris cells into lens starts with depigmentation and is followed by multiplication of the cells, which become arranged into a vesicle. Subsequently the cells in the posterior wall of the vesicle differentiate into lens fibres and, finally, a new lens is formed. Similarly in the chick (Van Deth, 1939, 1940) removal of the lens primordium from a 53-hour embryo and explantation of the eye-cup resulted in formation of a small lens from both iris epithelium and pigment layer of the retina. However, in the chick the lens-forming potency of the iris was not limited to the dorsal part, but extended also to the ventral rim.

Ultrastructural localization of nucleolar organizers during oogenesis in Xenopus laevis using a silver technique

1984 ◽  
Vol 65 (1) ◽  
pp. 73-93
Author(s):  
M. Boloukhere
Keyword(s):  
Xenopus Laevis ◽  
Transcriptional Activity ◽  
Morphological Changes ◽  
Organizer Region ◽  
Nucleolar Organizer Region ◽  
Electron Microscopic Level ◽  
Xenopus Laevis Oocytes ◽  
Electron Microscopic ◽  
Nucleolar Activity ◽  
Nucleolar Organizers

Silver staining at the electron microscopic level of the nucleolar organizers was carried out on Xenopus laevis oocytes at various stages of oogenesis. The results indicate that a positive reaction takes place exclusively in the dense fibrillar component of the extrachromosomal nucleoli. This constituent undergoes morphological changes of distribution and architecture, which have been correlated with modifications of the transcriptional activity of the nucleoli. When nucleolar activity is reduced, during previtellogenesis, this constituent appears as dense homogeneous spherules well-segregated from the granular component. In contrast, when nucleolar activity is high, during vitellogenesis, it forms an heterogeneous area with an ill-delimited outline: it is organized into a fibrillar core with emerging skein-like strings. It thus seems that this constituent remains silver-stained throughout oogenesis. These findings suggest that the method used would allow one to follow the evolution of the nucleolar organizer region (NOR) topography during oogenesis. Moreover, they point out facts that have relevance to the problem of the correlation between Ag stainability of NORs and nucleolar transcriptional activity.

scholarly journals Fibrous dysplasia of the maxilla: a case report

2016 ◽  
Vol 33 (01) ◽  
pp. 037-040
Author(s):  
R. Sousa ◽  
R. Tavares ◽  
C. Lins
Keyword(s):  
Computed Tomography ◽  
Fibrous Dysplasia ◽  
Maxillary Antrum ◽  
Morphological Changes ◽  
Bone Lesion ◽  
Facial Asymmetry ◽  
Posterior Wall ◽  
Normal Morphology ◽  
Normal Bone ◽  
Benign Bone Lesion

Abstract Introduction: Fibrous dysplasia is a benign bone lesion characterized by replacement of normal bone by fibrous connective tissue, and its diagnosis is based on clinical, radiological and histological findings. Objective: The aim of this study was to report a case of unilateral fibrous dysplasia in the maxilla, in the palate region, by using computed tomography. Results: On examination it was observed: a nodular lesion, with similar staining to the palatal mucosa with varicosities, regular edges, irm and painless. The radiographic indings on computed tomography showed one diffuse and heterogeneous thickening of the bony elements involving the hard palate extending to the posterior wall of the maxillary antrum. We opted for the preservation of the case, considering the age of the patient, the absence of facial asymmetry and lack of aesthetic and functional impairment. Conclusion: Thus, we emphasize that the knowledge of morphological changes is important for the diagnosis of bone pathologies, and the dentist must be familiar with the normal morphology of the structures and their possible abnormalities.

scholarly journals Expression of cell adhesion molecule E-cadherin in Xenopus embryos begins at gastrulation and predominates in the ectoderm.

1989 ◽  
Vol 108 (6) ◽  
pp. 2449-2458 ◽  
Author(s):  
Y S Choi ◽  
B Gumbiner
Keyword(s):  
Cell Adhesion ◽  
Epithelial Cell ◽  
Xenopus Laevis ◽  
Adhesion Molecule ◽  
Cell Adhesion Molecule ◽  
Cell Layer ◽  
Outer Cell ◽  
A6 Cells ◽  
Xenopus Embryos ◽  
E Cadherin

The expression of the Ca2+-dependent epithelial cell adhesion molecule E-cadherin (also known as uvomorulin and L-CAM) in the early stages of embryonic development of Xenopus laevis was examined. E-Cadherin was identified in the Xenopus A6 epithelial cell line by antibody cross-reactivity and several biochemical characteristics. Four independent mAbs were generated against purified Xenopus E-cadherin. All four mAbs recognized the same polypeptides in A6 cells, adult epithelial tissues, and embryos. These mAbs inhibited the formation of cell contacts between A6 cells and stained the basolateral plasma membranes of A6 cells, hepatocytes, and alveolar epithelial cells. The time of E-cadherin expression in early Xenopus embryos was determined by immunoblotting. Unlike its expression in early mouse embryos, E-cadherin was not present in the eggs or early blastula of Xenopus laevis. These findings indicate that a different Ca2+-dependent cell adhesion molecule, perhaps another member of the cadherin gene family, is responsible for the Ca2+-dependent adhesion between cleavage stage Xenopus blastomeres. Detectable accumulation of E-cadherin started just before gastrulation at stage 9 1/2 and increased rapidly up to the end of gastrulation at stage 15. In stage 15 embryos, specific immunofluorescence staining of E-cadherin was discernible only in ectoderm, but not in mesoderm and endoderm. The ectoderm at this stage consists of two cell layers. The outer cell layer of ectoderm was stained intensely, and staining was localized to the basolateral plasma membrane of these cells. Lower levels of staining were observed in the inner cell layer of ectoderm. The coincidence of E-cadherin expression with the process of gastrulation and its restriction to the ectoderm indicate that it may play a role in the morphogenetic movements of gastrulation and resulting segregation of embryonic germ layers.

scholarly journals CHANGES IN CELL FINE STRUCTURE DURING LENS REGENERATION IN XENOPUS LAEVIS

1965 ◽  
Vol 24 (2) ◽  
pp. 211-222 ◽  
Author(s):  
Jane Overton
Keyword(s):  
Fine Structure ◽  
Xenopus Laevis ◽  
Normal Development ◽  
Low Density ◽  
Morphological Complexity ◽  
Lens Fibers ◽  
Lens Regeneration ◽  
Lens Vesicle ◽  
Rough Er ◽  
Two Phases

Changes at the level of cell fine structure have been studied during lens regeneration in the toad, Xenopus laevis, where cornea gives rise to the new lens. The transformation of these cells may be divided into three phases. (1) In the cornea, flattened cells become cuboidal and rough endoplasmic reticulum increases in amount. (2) In the new lens vesicle, cisternae of the rough ER break down into vesicles, smooth-walled vesicles and free ribosomes increase in number, and mitochondria can become enlarged and irregular, then centrally attenuated. Rudimentary cilia form. (3) As new lens fibers form, ribosomes become very numerous and low density fibrous elements and dense clumps appear in the cytoplasm. These phases are accompanied by marked nucleolar changes. The changes during the 3rd phase are similar to changes in the lens during normal development. The first two phases show an unexpected morphological complexity.

Ontogeny and localization of the lens crystallins in Xenopus laevis lens regeneration

Development ◽  
1974 ◽  
Vol 32 (3) ◽  
pp. 783-794
Author(s):  
Samir K. Brahma ◽  
David S. McDevitt
Keyword(s):  
Xenopus Laevis ◽  
Rana Pipiens ◽  
Staining Method ◽  
Early Stage ◽  
Lens Protein ◽  
Lens Crystallins ◽  
Lens Regeneration ◽  
Stage 4 ◽  
Indirect Immunofluorescence Staining ◽  
Normal Lens

Ontogeny and localization of the lens crystallins, especially the γ-crystallins were investigated in Xenopus laevis lens regenerating system by the ‘indirect’ immunofluorescence staining method. Antibodies directed against Rana pipiens γ-crystallin antigen were used for the detection of this crystallin; the validity of such an experiment has been shown in a previous report. To detect total lens proteins we used X. laevis anti-total lens protein antibody. The regenerates were staged according to Freeman (1963) and the first positive reaction with both the two antisera was observed in an early stage-4 regenerate . The site of theimmunofluorescence reaction was nearly identical in both, suggesting that γ-crystallinsare one of the first, if not the first of the lens crystallins to appear during lens regeneration. The secondary fibres, when developed, showed less immunofluorescence than the primary fibres with R. pipiens anti-γ crystallin antibody, though the reaction was intense in the secondary fibres with X. laevis anti-total lens protein antibody. The intensity and distribution of immunofluorescence increased with the growth of the lens. With the R. pipiens anti-γ crystallin antibody, the lens epithelium did not show any immunofluorescence reaction at any stage of lens regeneration. With X. laevis anti-total lens protein antibody, the epithelium showed an immunofluorescence reaction earlier than in the normal lens development. With the two antisera we used, we did not observe any immunofluorescence outside the lens tissue.

Abstract 2438: Local Bipolar Atrial Electrogram Monitoring during the Extensive Encircling Pulmonary Vein Isolation: Implications of the ``QS Pattern” in the Local Bipolar Atrial Electrogram after the Ablation

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Kiyoshi Otomo ◽  
Hiroshi Taniguchi ◽  
Yasutoshi Nagata ◽  
Kikuya Uno ◽  
Yoshito Iesaka
Keyword(s):  
Pulmonary Vein ◽  
Morphological Changes ◽  
Posterior Wall ◽  
Local Lesion ◽  
Lesion Formation ◽  
Energy Delivery ◽  
Linear Ablation ◽  
Atrial Electrogram ◽  
Energy Application ◽  
Local Lesion Formation

BACKGROUND During the extensive encircling pulmonary vein (PV) isolation (EEPVI) for atrial fibrillation (AF), it is crucial to recognize whether or not a sufficient lesion was created by an ablation in each ablation site. The local electrogram (EG)-based criteria to predict a sufficient local lesion formation, however, remain to be established. This study was performed to define local EG-based criteria for the local lesion formation during the EEPVI for AF. METHODS Among 31 patients (pts) with AF who had successful EEPVI during coronary sinus pacing, bipolar local EGs at 2271 ablation sites (73+/-19 sites/pt, posterior wall (PW) of the left atrium (LA)/anterior LA-PV junction=976/1295 sites) before and after energy delivery were reviewed. In EEPVI, ipsilateral PVs, antral regions and parts of the PW of the LA were isolated as a whole by linear ablation at the PW of the LA and semi-linear ablation at the anterior LA-PV junction. Each energy application was performed with a temperature controlled mode (maximal temperature: 55 degrees Celsius, maximal output: 35 watt) and duration of 25 to 35 seconds. RESULTS After the ablation, all PVs, antral regions and parts of the PW of the LA were successfully isolated in all 31 pts (duration of each energy application: 31+/-3 sec/site, total energy application time: 37+/-10 min/pt). After the effective ablation at each site, the local EGs exhibited predominant reduction in the amplitude of positive deflection (Ap) as compared to that of negative deflection (An) (% reduction in Ap vs An: 91+/-10 vs 30+/-59%; p<0.01, Ap/An ratio before vs after ablation: 2.3+/-3.4 vs 0.3+/-0.1; p<0.01) as well as total amplitude reduction (67+/-22%) and EG widening (57+/-43%), and the morphology of the local EG changed to the ``QS” or ``rS” patterns. At 25 sites without those morphological changes, residual LA-PV conduction gaps were observed and additional ablations were required to achieve a complete EEPVI in 20 pts. CONCLUSION We propose that a morphological change of local EGs to ``QS” or ``rS” patterns with predominant attenuation of positive deflection of local EGs can reflect sufficient local lesion formation and can be one of the practical endpoints for energy delivery at each ablation site during the EEPVI.

Sperm incorporation in Xenopus laevis: characterisation of morphological events and the role of microfilaments

Zygote ◽  
2001 ◽  
Vol 9 (2) ◽  
pp. 167-181 ◽  
Author(s):  
Judith A. Boyle ◽  
Hui Chen ◽  
James R. Bamburg
Keyword(s):  
Plasma Membrane ◽  
Xenopus Laevis ◽  
Morphological Changes ◽  
Actin Dynamics ◽  
Cortical Granule ◽  
Granule Exocytosis ◽  
Sperm Binding ◽  
Transmission Electron ◽  
Latrunculin A ◽  
Cortical Granule Exocytosis

Scanning and transmission electron microscopy were used to determine the morphological changes in the egg plasma membrane associated with sperm binding, fusion and incorporation in Xenopus laevis. Sperm incorporation in Xenopus is rapid, occurring within 3-5 min following addition of sperm. Images have been obtained of both early sperm-egg interactions and fertilisation bodies. Additionally, two drugs that specifically alter F-actin dynamics, latrunculin and jasplakinolide, were used to determine whether sperm incorporation is a microfilament-dependent process. Jasplakinolide did not prevent sperm incorporation, cortical granule exocytosis or cortical contraction, suggesting these events can occur without depolymerisation of existing, stabilised filaments. Latrunculin A, which competes with thymosin β4 in ooplasm for binding actin monomer, did not inhibit cortical granule exocytosis, but blocked cortical contraction in 100% of eggs at a concentration of 5 μM. Although a single penetrating sperm was found on an egg pretreated in latrunculin, fertilisation bodies were never observed. At <5 μM latrunculin, many eggs did undergo cortical contraction with some exhibiting severe distortions of the plasma membrane and abnormal accumulations of pigment granules. Preincubation of eggs in jasplakinolide before latrunculin mitigated both these effects to some degree. However, eggs incubated in latrunculin either prior to or after insemination never progressed through first cleavage.

Sign in / Sign up

Export Citation Format

Share Document