|
|
|
|
|
|
|
||||
| Home Help Feedback Subscriptions Archive Search Table of Contents | ||||
|
Fig. 7. Engrailed expression prevents the differentiation of anterior midline
cells. (A) When cells derived from donors that ubiquitously express
Hedgehog (V2H/UAS-hh, brown and marked by a star) are implanted close
to the midline, they induce Engrailed expression (black) in midline cells
(arrowhead). Ventral view of a stage 12 embryo; anterior to the left.
(B) Transplanted cells (star) interfere with the differentiation of the
MP1 neurons. The axons of MP1 interneurons (thin arrow) are absent, causing a
gap in the MP1 fascicle (thick arrow). The Hedgehog-expressing cells only
interfere with the development of the MP1 neurons and midline glia. Midline
cells are labelled by expression of tau-ß-galactosidase (brown;
UAS-tau-lacZ). Ventral view of a stage 17 embryo. Only the MP1 axons
are in focus. (C-H) Left column, wild type; right column,
sim-GAL4/UAS-en. Embryos are at stage 17. (C) Axons (BP102,
brown) in the mature CNS can cross through an anterior commissure (arrowhead)
and a posterior commissure. (D) The expression of Engrailed (En, black)
in all midline cells prevents the formation of the anterior commissure
(arrowhead). (E) Midline glia (star) ensheath both commissures.
(F) Midline glia expressing Engrailed do not enwrap the remaining
commissure but lie on the dorsal surface of the CNS (star). Most midline glia
die (arrows indicate cell fragments). (G) In every segment Odd (brown)
is expressed in two lateral neurons, dMP2, and two midline neurons, MP1.
(H) Ectopic Engrailed in all midline cells abolishes the expression of
Odd in the MP1 neurons, but does not affect dMP2. Ventral views, anterior to
the left.
|
