scholarly journals Growth and Cellular Proliferation in the Early Rudiments of the Eye and the Lens

1952 ◽  
Vol s3-93 (23) ◽  
pp. 357-368
Author(s):  
B. I. BALINSKY
Keyword(s):  
Xenopus Laevis ◽  
Mitotic Index ◽  
Cellular Proliferation ◽  
Lens Development ◽  
Morphogenetic Movements ◽  
Duration Of Mitosis ◽  
Morphogenetic Movement ◽  
The Future ◽  
Lens Formation ◽  
Lens Material

1. The relation between growth, cellular proliferation, and morphogenetic movements was investigated in the case of lens formation in Elephantulus myurus jamesoni and Xenopus laevis. 2. For this purpose the volume of the eye cup and lens rudiments was estimated, counts of cells were made, and at the same time counts of cells in mitosis. The mitotic index was calculated, and the material wherever possible was treated statistically. 3. The lens rudiment grows at a greater rate than the eye cup rudiment during the stages in which the lens is being formed. The rate of cellular proliferation in the lens rudiment is also higher than in the eye cup rudiment. The size of the lens cells remains constant whilst the size of the eye cup cells diminishes during the period investigated (at least in Xenopus). 4. The mitotic index in the lens material is lower than in the eye cup material. This indicates that the duration of mitosis in relation to the interkinetic period is, in the eye cup rudiment, greater than in the lens rudiment. 5. The mitotic index in the lens material does not increase or decrease significantly during any stage of the lens development, nor were there found any other indications of an increased or decreased growth or proliferation of the lens material. It is therefore concluded that the formation of a visible lens rudiment is due to morphogenetic movement--contraction of a sheet of cells towards the centre of the future eye cup.

Activation of dorsal development by contact between the cortical dorsal determinant and the equatorial core cytoplasm in eggs of Xenopus laevis

Development ◽  
1997 ◽  
Vol 124 (8) ◽  
pp. 1543-1551 ◽  
Author(s):  
H. Kageura
Keyword(s):  
Xenopus Laevis ◽  
Dorsal Side ◽  
Equatorial Region ◽  
Normal Embryo ◽  
Dorsal Region ◽  
The Core ◽  
Dorsal Axis ◽  
The Future ◽  
Vegetal Pole ◽  
Cell Embryo

In eggs of Xenopus laevis, dorsal development is activated on the future dorsal side by cortical rotation, after fertilization. The immediate effect of cortical rotation is probably the transport of a dorsal determinant from the vegetal pole to the equatorial region on the future dorsal side. However, the identity and action of the dorsal determinant remain problematic. In the present experiments, individual isolated cortices from various regions of the unfertilized eggs and embryos were implanted into one of several positions of a recipient 8-cell embryo. The incidence of secondary axes was used not only to locate the cortical dorsal determinant at different times but also to locate the region of the core competent to respond to the dorsal determinant. The dorsal axis-inducing activity of the cortex occurred around the vegetal pole of the unfertilized egg. During cortical rotation, it shifted from there to a wide dorsal region. This is apparently the first evidence for the presence of a dorsal determinant in the egg cortex. The competence of the core of the 8-cell embryo was distributed in the form of gradient with the highest responsiveness at the equator. These results suggest that, in the normal embryo, dorsal development is activated by contact between the cortical dorsal determinant and the equatorial core cytoplasm, brought together through cortical rotation.

Crystallins during Xenopus laevis free lens formation

1988 ◽  
Vol 197 (3) ◽  
pp. 190-192 ◽  
Author(s):  
Samir Brahma ◽  
Horst Grunz
Keyword(s):  
Xenopus Laevis ◽  
Lens Formation

Morphological polarity of intercalating deep mesodermal cells in the organzer of Xenopus laevis gastrulae

1989 ◽  
Vol 47 ◽  
pp. 840-841
Author(s):  
Ray Keller ◽  
John Shih ◽  
Paul Wilson
Keyword(s):  
Xenopus Laevis ◽  
Time Lapse ◽  
Light Level ◽  
Cell Labelling ◽  
Fluorescent Compound ◽  
Morphogenetic Movements ◽  
Tissue Interactions ◽  
Convergence And Extension ◽  
Morphological Polarity ◽  
Cell Intercalation

The dorsal lip of the blastopore constitutes the “organizer” of the amphibian body plan, both in terms of its tissue interactions and its morphogenetic movements of convergence and extension during gastrulation. This tissue autonomously narrows (converges) and lengthens (extends) during early development, functioning prominently in the morphogenetic movements of both gastrulation and neurulation Xenopus laevis. High resolution time-lapse recording of cell behavior in cultured explants and cell labelling studies have shown that the movements of convergence and extension are produced by radial intercalation of cells, in which several layers rearrange to produce fewer layers of greater area, and by mediolateral intercalation of cells, in which several rows of cells rearrange to produce a narrower, longer array. By labelling individual cells with the fluorescent compound, DiI, and making low light level recordings, we found that cells of the notochord intercalate mediolaterally using polarized protrusive activity at their internal medial or lateral ends. Thus polarized protrusive activity appears to play a major role in mediolateral cell intercalation after the boundary between the notochord and somites forms in the late gastrula stage.We examine further the morphology of the deep mesodermal cells with scanning electron microscopy at earlier stages, to search for morphological manifestations of a similar polarity of protrusive activity. The dorsal deep mesodermal cells of early gastrulae were exposed by rapidly pulling the. epithelial endoderm off the deep cells with forceps, in Danilchik's solution, and fixing the embryo within 15 seconds in 2% glutaraldehyde in 0.1 M sodium cacodylate buffer (pH 7.4) as described previously. The dorsal deep cells adjacent to the epithelium are elongate and aligned parallel to one another and to the circumference of the glastopore (Fig. 1). The medial and lateral ends bear broad, lamelliform protrusions (large pointers, Fig. 1, 2) whereas the anterior and posterior ends bear numerous small filiform protrusions (small pointers, Fig. 1, 2). This characteristic morphology is found only in the dorsal marginal zone, which undergoes convergence and extension by mediolateral intercalation.

Roles of Cortical and Subcortical Components in Cleavage Furrow Formation in Amphibia

1972 ◽  
Vol 11 (2) ◽  
pp. 543-556
Author(s):  
TSUYOSHI SAWAI
Keyword(s):  
Surface Layer ◽  
Xenopus Laevis ◽  
Species Specificity ◽  
Cleavage Furrow ◽  
Entire Surface ◽  
Animal Pole ◽  
The Future ◽  
Vegetal Pole ◽  
Triturus Pyrrhogaster

In the eggs of the newt, Triturus pyrrhogaster, 2 separate factors are recognized which take part in cleavage furrow formation. (1) The inductive capacity for the furrow formation by the cytoplasm lying under the cortex along the cleavage furrow (FIC); and (2) the reactivity of the overlying cortex to form a furrow in response to FIC. (1) FIC. The inductive capacity is shown by the fact that FIC induces a furrow on whichever part of the surface under which FIC is transplanted. FIC is distributed along the cleavage furrow and even extends along the future furrow plane ahead of the furrow tip. The distance FIC precedes the furrow tip is about 1.0 mm in the animal hemisphere and is less in the vegetal hemisphere. In the direction at right angles to the furrow plane, FIC does not spread more than 0.1 mm. FIC is also present in the eggs of Xenopus laevis. Species specificity of FIC for induction is not found between Triturus and Xenopus. (2) Surface layer. At the onset of the first cleavage, the reactivity of the cortex to form the furrow in answer to FIC induction is localized on the animal pole region. The reactivity of the cortex propagates medially as a belt along the surface towards the vegetal pole with the advancing tip of the cleavage furrow. After the furrow is completed, the reactivity begins to be lost from the animal pole region, and eventually over the entire surface. The reactivity, however, reappears on the animal pole region simultaneously with the second cleavage.

A reinvestigation of some of the tissue movements involved in the formation of the neural tube and the eye/lens system of Triturus alpestris and Xenopus laevis

Development ◽  
1966 ◽  
Vol 16 (3) ◽  
pp. 431-438
Author(s):  
R. S. Lowery
Keyword(s):  
Xenopus Laevis ◽  
Neural Tube ◽  
Subsequent Development ◽  
Neural Plate ◽  
Eye Lens ◽  
Optic Vesicle ◽  
Lens System ◽  
Lens Development ◽  
Triturus Alpestris ◽  
Optic Cup

Since the beginning of the century the generally accepted scheme of eye/lens development has been that proposed by Spemann (1901) and later confirmed by numerous workers. According to this scheme the two presumptive components of the definitive eye, the optic cup and the lens, are spatially separated at the flat neural plate stage. They later come into apposition as a result of tissue movements which occur during the formation of the neural tube; the optic vesicle then provides an inductive stimulus for the subsequent development of the presumptive lens tissue. Spemann's suggestions concerning the tissue movements involved in the early formation of the eye/lens system do not appear to have been fundamentally questioned until the publication of a number of papers by Chanturishvili (1943, 1949,1958,1959,1962), although the theory of lens induction has been modified by workers such as Liedke (1955), Jacobson (1963) and von Woellwarth (1962).

Comparison of Mitotic Index, In Vitro Bromodeoxyuridine Labeling, and MIB-1 Assays to Quantitate Proliferation in Breast Cancer

1999 ◽  
Vol 17 (2) ◽  
pp. 470-470 ◽  
Author(s):  
Ann D. Thor ◽  
Shuqing Liu ◽  
Dan H. Moore II ◽  
Susan M. Edgerton
Keyword(s):  
Breast Cancer ◽  
Lymph Node ◽  
Mitotic Index ◽  
Cellular Proliferation ◽  
Nodal Status ◽  
Node Negative ◽  
Node Positive ◽  
Brdu Labeling ◽  
Mib 1

PURPOSE: To investigate the hypothesis that in vitro bromodeoxyuridine (BrDu) labeling might be superior to MIB-1 immunostaining for prognostic value, because it more selectively labels cells during the S phase. METHODS: Four hundred eighty-six patients with breast cancers (59% lymph node-negative, 41% lymph node-positive) surgically excised between 1988 and 1993 (median follow-up, 62 months) were evaluated for cellular proliferation using prospective in vitro BrDu uptake assays, retrospective mitotic indices, and MIB-1 labeling. RESULTS: MIB-1, BrDu labeling, and mitotic index–derived proliferation data were highly correlated. Each was similarly associated with most other markers of prognosis, although these relationships were not identical. By univariate analysis, nodal status was the most significant prognostic variable for all patients. Higher BrDu labeling index, MIB-1 immunolabeling, and mitotic index were also associated with shortened disease-free survival (DFS) and disease-specific survival for the entire patient group, as well as for node-negative patients. The association between cellular proliferation and survival was much weaker for node-positive patients. Multivariate models confirmed that nodal status, tumor size, and proliferation data predicted survival in all patients as well as those with node-negative disease, although MIB-1 was somewhat more closely associated with outcome than mitotic index or in vitro BrDu data. For patients with T1N0M0 disease (n = 172), the only significant predictors of DFS were proliferation rate (mitotic index or MIB-1) and tumor grade. CONCLUSIONS: Proliferation rate predicts recurrence and survival in breast cancer. This effect is more pronounced in node-negative patients. In vitro BrDu data are not superior to MIB-1 and mitotic counting.

scholarly journals The Reaper-Binding Protein Scythe Modulates Apoptosis and Proliferation during Mammalian Development

2005 ◽  
Vol 25 (23) ◽  
pp. 10329-10337 ◽  
Author(s):  
Fabienne Desmots ◽  
Helen R. Russell ◽  
Youngsoo Lee ◽  
Kelli Boyd ◽  
Peter J. McKinnon
Keyword(s):  
Cell Death ◽  
Drosophila Melanogaster ◽  
Programmed Cell Death ◽  
Xenopus Laevis ◽  
Cellular Proliferation ◽  
Nuclear Protein ◽  
Normal Development ◽  
Mammalian Development ◽  
Developmental Defects ◽  
Cell Extracts

ABSTRACT Scythe (BAT3 [HLA-B-associated transcript 3]) is a nuclear protein that has been implicated in apoptosis, as it can modulate Reaper, a central apoptotic regulator in Drosophila melanogaster. While Scythe can markedly affect Reaper-dependent apoptosis in Xenopus laevis cell extracts, the function of Scythe in mammals is unknown. Here, we report that inactivation of Scythe in the mouse results in lethality associated with pronounced developmental defects in the lung, kidney, and brain. In all cases, these developmental defects were associated with dysregulation of apoptosis and cellular proliferation. Scythe − / − cells were also more resistant to apoptosis induced by menadione and thapsigargin. These data show that Scythe is critical for viability and normal development, probably via regulation of programmed cell death and cellular proliferation.

scholarly journals Role of the hypoxia response pathway in lens formation during embryonic development of Xenopus laevis

FEBS Open Bio ◽  
2013 ◽  
Vol 3 (1) ◽  
pp. 490-495 ◽  
Author(s):  
Kazunobu Baba ◽  
Taichi Muraguchi ◽  
Susumu Imaoka
Keyword(s):  
Embryonic Development ◽  
Xenopus Laevis ◽  
Hypoxia Response ◽  
Lens Formation
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