Normal Table of Xenopus Laevis (Daudin). A Systematical and Chronological Survey of the Development from the Fertilized Egg Till the End of Metamorphosis.P. D. Nieuwkoop , J. Faber

1958 ◽  
Vol 33 (1) ◽  
pp. 85-85 ◽  
Author(s):  
Arnold B. Grobman
Keyword(s):  
Xenopus Laevis ◽  
Normal Table ◽  
Fertilized Egg

Normal Table of Xenopus Laevis (Daudin)

Copeia ◽  
1958 ◽  
Vol 1958 (1) ◽  
pp. 65 ◽  
Author(s):  
P. D. Nieuwkoop ◽  
J. Faber
Keyword(s):  
Xenopus Laevis ◽  
Normal Table

Normal table of Xenopus laevis (Daudin)

1995 ◽  
Vol 11 (10) ◽  
pp. 418 ◽  
Author(s):  
J.B. Gurdon
Keyword(s):  
Xenopus Laevis ◽  
Normal Table

Transfer of Primordial Germ-cells in Xenopus laevis

Development ◽  
1961 ◽  
Vol 9 (4) ◽  
pp. 634-641
Author(s):  
A. W. Blackler ◽  
M. Fischberg
Keyword(s):  
Xenopus Laevis ◽  
Germ Cells ◽  
Germ Line ◽  
Primordial Germ Cells ◽  
Dorsal Region ◽  
Blastula Stage ◽  
Early Embryonic Stage ◽  
Sex Cells ◽  
Fertilized Egg ◽  
Dorsal Mesentery

There have been many claims for the segregation of Anuran primordial germcells at an early embryonic stage. Most authors agree that these cells may be distinguished with ease in the most dorsal region of the larval endoderm and, somewhat later in development, at the base of the dorsal mesentery and in the undifferentiated gonad (see review by Johnston, 1951). Bounoure (1934) and Blackler (1958) claim to have traced the origin of the primordial germ-cells as early in development as the late blastula stage and to have recognized cell inclusions that become restricted to the germ line at all stages between the fertilized egg and the late blastula. As pointed out by Everett (1945), some workers in this field of embryological study have firmly denied the existence of primordial germ-cells, while others have been cautious of accepting the principle that these cells give rise to any of the definitive sex-cells (gametes).

scholarly journals Preservation of Xenopus laevis rDNA-containing plasmid, pXlr101A, injected into the fertilized egg of Xenopus laevis.

1986 ◽  
Vol 11 (2) ◽  
pp. 109-114 ◽  
Author(s):  
Kosuke Tashiro ◽  
Masami Inoue ◽  
Yoshiyuki Sakaki ◽  
Koichiro Shiokawa
Keyword(s):  
Xenopus Laevis ◽  
Fertilized Egg

Evidence for a functional role of the cytoskeleton in determination of the dorsoventral axis in Xenopus laevis eggs

Development ◽  
1983 ◽  
Vol 77 (1) ◽  
pp. 15-37
Author(s):  
Geertje A. Ubbels ◽  
K. Hara ◽  
C. H. Koster ◽  
M. W. Kirschner
Keyword(s):  
Functional Role ◽  
Normal Development ◽  
Cytological Study ◽  
Time Lapse ◽  
Microtubule Assembly ◽  
Dorsoventral Axis ◽  
Normal Table ◽  
Fertilized Egg

A normal table of events of the first cleavage period in the fertilized egg (cf. Gerhart, 1980) has been completed (cf. Table I) by studying external and internal features. Through a cytological study of eggs fixed after video time-lapse observation such featurescan directly be correlated and it has been shown that the first postfertilization wave (PFW) reflects spermaster growth, which causes rearrangements of animal yolk material. Thismay, in conjunction with the interaction of the spermaster rays with the cortex, define, in time as well as in space, the asymmetric cortical contraction which we suppose to evoke asymmetry in the animal hemisphere by formation of the vitelline wall (Pasteels, 1964) and in the vegetal hemisphere by formation of the Vegetal Dorsalising Centre (Kirschneret al. 1981). Neither prick-activated eggs nor fertilized eggs incubated in vinblastine develop a spermaster. Under these conditions abnormal cytoplasmic segregation may be directed by gravity alone. For normal development the activated egg must in some way, for instance through the sperm centriole, organize microtubule assembly into a monaster. The centriole actsas a microtubule-organizing centre in structuring the egg's cytoskeleton, and through this directs localization of the various yolk components, in time as well as in space. In egg rotation experiments performed under appropriate conditions, the cytoskeleton is disturbed and yolk rearranges under gravity till a new equilibrium is established which determines a new dorsoventral polarity. Such experiments also show that neither the dorsal cytoplasm nor the grey crescent cortex act as the ultimate dorsal determinants, since their localization is unaltered upon rotation, whereas the overall yolk distribution is significantly changed.

scholarly journals PLC and IP3-evoked Ca2+ release initiate the fast block to polyspermy in Xenopus laevis eggs

2018 ◽  
Vol 150 (9) ◽  
pp. 1239-1248 ◽  
Author(s):  
Katherine L. Wozniak ◽  
Maiwase Tembo ◽  
Wesley A. Phelps ◽  
Miler T. Lee ◽  
Anne E. Carlson
Keyword(s):  
Developmental Biology ◽  
Endoplasmic Reticulum ◽  
Xenopus Laevis ◽  
Potent Inhibitor ◽  
Extracellular Milieu ◽  
African Clawed Frog ◽  
Inositol 1,4,5 Trisphosphate ◽  
Clawed Frog ◽  
Normal Embryonic Development ◽  
Fertilized Egg

The prevention of polyspermy is essential for the successful progression of normal embryonic development in most sexually reproducing species. In external fertilizers, the process of fertilization induces a depolarization of the egg’s membrane within seconds, which inhibits supernumerary sperm from entering an already-fertilized egg. This fast block requires an increase of intracellular Ca2+ in the African clawed frog, Xenopus laevis, which in turn activates an efflux of Cl− that depolarizes the cell. Here we seek to identify the source of this intracellular Ca2+. Using electrophysiology, pharmacology, bioinformatics, and developmental biology, we explore the requirement for both Ca2+ entry into the egg from the extracellular milieu and Ca2+ release from an internal store, to mediate fertilization-induced depolarization. We report that although eggs express Ca2+-permeant ion channels, blockade of these channels does not alter the fast block. In contrast, insemination of eggs in the presence of Xestospongin C—a potent inhibitor of inositol 1,4,5-trisphosphate (IP3)-induced Ca2+ release from the endoplasmic reticulum (ER)—completely inhibits fertilization-evoked depolarization and increases the incidence of polyspermy. Inhibition of the IP3-generating enzyme phospholipase C (PLC) with U73122 similarly prevents fertilization-induced depolarization and increases polyspermy. Together, these results demonstrate that fast polyspermy block after fertilization in X. laevis eggs is mediated by activation of PLC, which increases IP3 and evokes Ca2+ release from the ER. This ER-derived Ca2+ then activates a Cl− channel to induce the fast polyspermy block. The PLC-induced cascade of events represents one of the earliest known signaling pathways initiated by fertilization.

Cytological analyses of factors which determine the number of primordial germ cells (PGCs) in Xenopus laevis

Development ◽  
1985 ◽  
Vol 90 (1) ◽  
pp. 251-265
Author(s):  
Yasuko Akita ◽  
Masami Wakahara
Keyword(s):  
Xenopus Laevis ◽  
Germ Cells ◽  
Germ Plasm ◽  
Primordial Germ Cells ◽  
Somatic Cells ◽  
Cell Stage ◽  
Unknown Mechanism ◽  
Fertilized Egg ◽  
Number Of Cells ◽  
Experimentally Induced

Correlation of the number of primordial germ cells (PGCs) at stage 47 with the amount of germ plasm at the 8-cell stage and with the number of the germ-plasm-containing cells (GPCCs) was analysed using two different laboratory-raised colonies of Xenopus laevis, HD and J groups. The average number of PGCs in J group tadpoles was significantly larger than that in HD group tadpoles. The amount of germ plasm in J group embryos was also demonstrated to be larger than in HD group embryos. The amount of germ plasm was related positively to the number of GPCCs at the 8-cell stage and to the resulting number of PGCs; embryos which contained larger amounts of germ plasm developed larger numbers of PGCs at stage 47. The average number of PGCs in experimentally induced triploid tadpoles was exactly twothirds of that in normal diploid tadpoles. Furthermore, in somatic cells (e.g. epidermis, muscle, pancreas), the number of cells in the triploid was also two-thirds of that in diploid tadpoles. These findings suggest that the number of PGCs is regulated by at least two different mechanisms: first, the number of PGCs is primarily specified by the intrinsic amount of germ plasm in the fertilized egg. Second, it is regulated by an unknown mechanism which controls the total number of cells of whole embryos, such as the nucleocytoplasmic ratio.

Normal Table of Xenopus Laevis (Daudin)

2020 ◽  
Author(s):  
John Gerhart ◽  
Marc Kirschner
Keyword(s):  
Xenopus Laevis ◽  
Normal Table

Androgen-induced plasticity at a “vocal” neuromuscular synapse

1994 ◽  
Vol 52 ◽  
pp. 32-33
Author(s):  
Darcy B. Kelley ◽  
Martha L. Tobias ◽  
Mark Ellisman
Keyword(s):  
Xenopus Laevis ◽  
Motor Neurons ◽  
Sexual Differentiation ◽  
Molecular Basis ◽  
Neuromuscular Synapse ◽  
Sexually Dimorphic ◽  
Intracellular Protein ◽  
Developmental Program ◽  
Androgen Action ◽  
Clawed Frog

Brain and muscle are sexually differentiated tissues in which masculinization is controlled by the secretion of androgens from the testes. Sensitivity to androgen is conferred by the expression of an intracellular protein, the androgen receptor. A central problem of sexual differentiation is thus to understand the cellular and molecular basis of androgen action. We do not understand how hormone occupancy of a receptor translates into an alteration in the developmental program of the target cell. Our studies on sexual differentiation of brain and muscle in Xenopus laevis are designed to explore the molecular basis of androgen induced sexual differentiation by examining how this hormone controls the masculinization of brain and muscle targets.Our approach to this problem has focused on a highly androgen sensitive, sexually dimorphic neuromuscular system: laryngeal muscles and motor neurons of the clawed frog, Xenopus laevis. We have been studying sex differences at a synapse, the laryngeal neuromuscular junction, which mediates sexually dimorphic vocal behavior in Xenopus laevis frogs.

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