Faculty Opinions recommendation of The RNaseIII enzyme Dicer is required for morphogenesis but not patterning of the vertebrate limb.

2005 ◽  
Author(s):  
Cliff Ragsdale
Keyword(s):  
Vertebrate Limb

scholarly journals Coordinate Roles for LIM Homeobox Genes in Directing the Dorsoventral Trajectory of Motor Axons in the Vertebrate Limb

Cell ◽  
2000 ◽  
Vol 102 (2) ◽  
pp. 161-173 ◽  
Author(s):  
Artur Kania ◽  
Randy L Johnson ◽  
Thomas M Jessell
Keyword(s):  
Homeobox Genes ◽  
Motor Axons ◽  
Vertebrate Limb

FGF-4 maintains polarizing activity of posterior limb bud cells in vivo and in vitro

Development ◽  
1993 ◽  
Vol 119 (1) ◽  
pp. 199-206 ◽  
Author(s):  
A. Vogel ◽  
C. Tickle
Keyword(s):  
Posterior Margin ◽  
Anterior Margin ◽  
Marked Decrease ◽  
Mesenchymal Cells ◽  
Apical Ectodermal Ridge ◽  
Limb Bud ◽  
Posterior Limb ◽  
Vertebrate Limb

The polarizing region is a major signalling tissue involved in patterning the tissues of the vertebrate limb. The polarizing region is located at the posterior margin of the limb bud and can be recognized by its ability to induce additional digits when grafted to the anterior margin of a chick limb bud. The signal from the polarizing region operates at the tip of the bud in the progress zone, a zone of undifferentiated mesenchymal cells, maintained by interactions with the apical ectodermal ridge. A number of observations have pointed to a link between the apical ectodermal ridge and signalling by the polarizing region. To test this possibility, we removed the posterior apical ectodermal ridge of chick wing buds and assayed posterior mesenchyme for polarizing activity. When the apical ectodermal ridge is removed, there is a marked decrease in polarizing activity of posterior cells. The posterior apical ectodermal ridge is known to express FGF-4 and we show that the decrease in polarizing activity of posterior cells of wing buds that normally follows ridge removal can be prevented by implanting a FGF-4-soaked bead. Furthermore, we show that both ectoderm and FGF-4 maintain polarizing activity of limb bud cells in culture.

Ultrastructural analysis of the apical ectodermal ridge during vertebrate limb morphogenesis

Development ◽  
1977 ◽  
Vol 41 (1) ◽  
pp. 223-232
Author(s):  
John F. Fallon ◽  
Robert O. Kelley
Keyword(s):  
Electron Microscopy ◽  
Gap Junctions ◽  
Freeze Fracture ◽  
Apical Ectodermal Ridge ◽  
Structural Requirements ◽  
Limb Morphogenesis ◽  
Vertebrate Limb ◽  
The Difference ◽  
Freeze Fracture Electron Microscopy ◽  
Fracture Electron

The fine structure of the apical ectodermal ridge of five phylogenetically divergent orders of mammals and two orders of birds was examined using transmission and freeze fracture electron microscopy. Numerous large gap junctions were found in all apical ectodermal ridges studied. This was in contrast to the dorsal and ventral limb ectoderms where gap junctions were always very small and sparsely distributed. Thus, gap junctions distinguish the inductively active apical epithelium from the adjacent dorsal and ventral ectoderms. The distribution of gap junctions in the ridge was different between birds and mammals but characteristic within the two classes. Birds, with a pseudostratified columnar apical ridge, had the heaviest concentration of gap junctions at the base of each ridge cell close to the point where contact was made with the basal lamina. Whereas mammals, with a stratified cuboidal to squamous apical ridge, had a more uniform distribution of gap junctions throughout the apical epithelium. The difference in distribution for each class may reflect structural requirements for coupling of cells in the entire ridge. We propose that all cells of the apical ridges of birds and mammals are electrotonically and/or metabolically coupled and that this may be a requirement for the integrated function of the ridge during limb morphogenesis.

Patched 1 is a crucial determinant of asymmetry and digit number in the vertebrate limb

Development ◽  
2009 ◽  
Vol 136 (20) ◽  
pp. 3515-3524 ◽  
Author(s):  
N. C. Butterfield ◽  
V. Metzis ◽  
E. McGlinn ◽  
S. J. Bruce ◽  
B. J. Wainwright ◽  
...  
Keyword(s):  
Digit Number ◽  
Vertebrate Limb ◽  
Patched 1

scholarly journals Proprioception In Insects

1938 ◽  
Vol 15 (1) ◽  
pp. 114-131 ◽  
Author(s):  
J. W. S. PRINGLE
Keyword(s):  
Contact Pressure ◽  
Mode Of Action ◽  
Mechanical Model ◽  
Campaniform Sensilla ◽  
Chemical Substances ◽  
Parallel Orientation ◽  
Model Based ◽  
Vertebrate Limb ◽  
Olfactory Stimuli ◽  
Anatomical Arrangement

1. The campaniform sensilla on the legs of Periplaneta are similar in action to those on the palps, and respond to strains in the cuticle. 2. They are arranged in groups at the joints, with parallel orientation of the sensilla of a group. 3. Tests with various chemical substances show a complete absence of sensitivity to olfactory stimuli. 4. A theory is given of the mode of action of the sensilla in terms of a mechanical model based on their observed structure. Each group of parallel sensilla should act as a unit, responding to those forces which have a compression component of shear in the direction of their long diameters. 5. This theory makes it possible to predict the behaviour of the sensilla from their anatomical arrangement. Most if not all the groups on the legs are so arranged as to be sensitive to the forces present when the insect is standing on the ground. 6. The sensilla probably provide the basis for the sense of contact pressure postulated by Holst (1935), Hoffmann (1933), Crozier & Stier (1928-9), Fraenkel (1932) and others. 7. Comparison of this proprioceptive mechanism with that of the vertebrate limb reveals an absence of qualitative sensitivity that may have an important bearing on the question of the evolution of behaviour.

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