The beginning of pattern formation in the Drosophila compound eye: the morphogenetic furrow and the second mitotic wave

Development ◽  
1991 ◽  
Vol 113 (3) ◽  
pp. 841-850 ◽  
Author(s):  
T. Wolff ◽  
D.F. Ready

Events in the morphogenetic furrow set the stage for all subsequent compound eye development in Drosophila. The periodic pattern of the adult eye begins in the furrow with the spaced initiation of ommatidial rudiments, the preclusters. A wave of mitosis closely follows the furrow. A cell-by-cell analysis reveals details of these events. Early stages of ommatidial assembly can be resolved using a lead sulfide stain. Overt ommatidial organization begins in the morphogenetic furrow as cells gather into periodically spaced concentric aggregates. A stereotyped sequence of cell rearrangements converts these aggregates into preclusters. In the furrow, new rows of ommatidia are initiated at the equator and grow as new clusters are added to the peripheral ends. Mitotic labeling using BrdU feeds shows that all cells not incorporated into a precluster divide. BrdU injections show that cells divide roughly simultaneously between two adjacent rows of ommatidia.

Development ◽  
1995 ◽  
Vol 121 (9) ◽  
pp. 3045-3055 ◽  
Author(s):  
L. Zheng ◽  
J. Zhang ◽  
R.W. Carthew

Coordinated morphogenesis of ommatidia during Drosophila eye development establishes a mirror-image symmetric pattern across the entire eye bisected by an anteroposterior equator. We have investigated the mechanisms by which this pattern formation occurs and our results suggest that morphogenesis is coordinated by a graded signal transmitted bidirectionally from the presumptive equator to the dorsal and ventral poles. This signal is mediated by frizzled, which encodes a cell surface transmembrane protein. Mosaic analysis indicates that frizzled acts non-autonomously in an equatorial to polar direction. It also indicates that relative levels of frizzled in photoreceptor cells R3 and R4 of each ommatidium affect their positional fate choices such that the cell with greater frizzled activity becomes an R3 cell and the cell with less frizzled activity becomes an R4 cell. Moreover, this bias affects the choice an ommatidium makes as to which direction to rotate. Equator-outwards progression of elav expression and expression of the nemo gene in the morphogenetic furrow are regulated by frizzled, which itself is dynamically expressed about the morphogenetic furrow. We propose that frizzled mediates a bidirectional signal emanating from the equator.


Development ◽  
2000 ◽  
Vol 127 (8) ◽  
pp. 1681-1689 ◽  
Author(s):  
N.M. White ◽  
A.P. Jarman

During Drosophila eye development, the proneural gene atonal specifies founding R8 photoreceptors of individual ommatidia, evenly spaced relative to one another in a pattern that prefigures ommatidial organisation in the mature compound eye. Beyond providing neural competence, however, it has remained unclear to what extent atonal controls specific R8 properties. We show here that reduced Atonal function gives rise to R8 photoreceptors that are functionally compromised: both recruitment and axon pathfinding defects are evident. Conversely, prolonged Atonal expression in R8 photoreceptors induces defects in inductive recruitment as a consequence of hyperactive EGFR signalling. Surprisingly, such prolonged expression also results in R8 pattern formation defects in a process associated with both Hedgehog and Receptor Tyrosine Kinase signalling. Our results strongly suggest that Atonal regulates signalling and other properties of R8 precursors.


Development ◽  
1997 ◽  
Vol 124 (2) ◽  
pp. 271-278 ◽  
Author(s):  
F. Pignoni ◽  
S.L. Zipursky

The Drosophila decapentaplegic (dpp) gene, encoding a secreted protein of the transforming growth factor-beta (TGF-beta) superfamily, controls proliferation and patterning in diverse tissues, including the eye imaginal disc. Pattern formation in this tissue is initiated at the posterior edge and moves anteriorly as a wave; the front of this wave is called the morphogenetic furrow (MF). Dpp is required for proliferation and initiation of pattern formation at the posterior edge of the eye disc. It has also been suggested that Dpp is the principal mediator of Hedgehog function in driving progression of the MF across the disc. In this paper, ectopic Dpp expression is shown to be sufficient to induce a duplicated eye disc with normal shape, MF progression, neuronal cluster formation and direction of axon outgrowth. Induction of ectopic eye development occurs preferentially along the anterior margin of the eye disc. Ectopic Dpp clones situated away from the margins induce neither proliferation nor patterning. The Dpp signalling pathway is shown to be under tight transcriptional and post-transcriptional control within different spatial domains in the developing eye disc. In addition, Dpp positively controls its own expression and suppresses wingless transcription. In contrast to the wing disc, Dpp does not appear to be the principal mediator of Hedgehog function in the eye.


The Analyst ◽  
2021 ◽  
Author(s):  
Wen Qin ◽  
Hans-Joachim Stärk ◽  
Thorsten Reemtsma

A new method for determining the concentration of elements in single cells by the SC-ICP-TOF-MS method based on a metal-containing stain as a cell volume proxy has been developed and validated.


Development ◽  
1997 ◽  
Vol 124 (23) ◽  
pp. 4819-4826 ◽  
Author(s):  
N.M. Bonini ◽  
Q.T. Bui ◽  
G.L. Gray-Board ◽  
J.M. Warrick

The fly eyes absent (eya) gene which is essential for compound eye development in Drosophila, was shown to be functionally replaceable in eye development by a vertebrate Eya homolog. The relationship between eya and that of the eyeless gene, a Pax-6 homolog, critical for eye formation in both flies and man, was defined: eya was found to be essential for eye formation by eyeless. Moreover, eya could itself direct ectopic eye formation, indicating that eya has the capacity to function as a master control gene for eye formation. Finally, we show that eya and eyeless together were more effective in eye formation than either gene alone. These data indicate conservation of the pathway of eya function between flies and vertebrates; they suggest a model whereby eya/Eya gene function is essential for eye formation by eyeless/Pax-6, and that eya/Eya can in turn mediate, via a regulatory loop, the activity of eyeless/Pax-6 in eye formation.


1973 ◽  
Vol 4 (2) ◽  
pp. 87-90 ◽  
Author(s):  
Rolf Elofsson

AbstractThe ultrastructure of the primary pigment cells of the compound eye of Lepisma saccharina is described. The cells are four in number. The pigment granules are contained in fingerlike protrusions from the pigment cells. These protrusions project into the enlarged basal lamina surrounding the ommatidial top. The large basal lamina could have given the impression of a cell (called corneagen) in the light microscope.


1997 ◽  
Vol 3 (S2) ◽  
pp. 1129-1130
Author(s):  
John Archie Pollock ◽  
Bejon T. Maneckshana ◽  
Teresa E. Leonardo

The compound eye of the fruit fly, Drosophila melanogaster, is composed of a highly ordered array of facets (FIG. 1), each containing a precise set of neurons and supporting cells. The eye arises during the third larval instar from an undifferentiated epithelium, the eye imaginai disc, which is connected to the brain via the optic stalk (FIG. 2). During eye development, movement of the morphogenetic furrow, progressive recruitment of specific cell types and the growth of photoreceptor axons into the brain are each dynamic processes that are routinely studied indirectly in fixed tissues. While stereotyped development and the ‘crystalline’ like structure of the eye facilitates this analysis, certain experiments are hindered by the inability to observe developmental processes as they occur. To overcome this limitation, we have combined organ culture with advanced microscopy tools to enable the observation of eye development in living tissue.


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