transcripts are detected in medulla neuropil glial cells as well as in streams of glial cells migrating within the outer proliferation center to reach the medulla neuropil.
In the larval visual system, gcm
transcript is expressed not only in specific glial subtypes, but also in the lineage that gives rise to lamina neurons.
expression is observed in the larval optic lobe in some glial subtypes and in a lineage that gives rise to lamina neurons. Expression begins in glial precursor cells at the lamina margins that will give rise to epithelial and marginal glial cells. Expression is also observed in neruonal precursors in the lamina.
expressed first in presumptive glial cell of dbd lineage after decrease in nub
transcripts are first detected by in situ hybridization in the head region of the embryo at the end of the blastoderm stage. At stage 10, expression is still very prominent in the procephalic mesoderm. Additionally staining is seem in one cell per hemisegment in the lateral ectoderm which may correspond to PNS. A second, more medially located cell, may be the longitudinal glioblast. By stage 11, expression decreases in the hemocyte lineage and becomes more prominent in glial cells of the PNS and CNS. The staining pattern appears d fferent in the thoracic and abdominal segments reflecting the different organization of the glial cells. No signal is observed in cells migrating from the procephalic mesoderm after stage 11.
transcripts are expressed in glial precursors and immature glial cells during a short period of gliogenesis. Expression is first detected in early stage 11 in the longitudinal glioblast. By mid stage 11, 2-3 other cells per hemisegment express gcm
. Two of these have been identified as NB6-4 and the medial-most cell body glial cell (VUM support cell). By early stage 12, expression is detected in several other cells which are also developing glial cells. Expression fades during stage 12 and is hardly detectable in stage 13. Enhancer trap expression was used to trace the gcm
-expressing cells to later developmental stages. It was found that gcm
is expressed in all glial precursors and immature glial cells except those derived from the mesectoderm. Outside of the CNS, gcm
is expressed in the most anterior region of the presumptive mesoderm beginning at the cellular blastoderm stage, in the brain neurogenic region, and in the PNS neurogenic region.
transcripts are initially expressed in an anterior ventral patch in the cellular blastoderm embryo. During gastrulation, these cells invaginate at the end of the ventral furrow just anterior to the cephalic furrow in an area that gives rise to the cephalic mesoderm. Cephalic expression fades after stage 10. During stages 11-12, in each hemisegment, two patches of 3-5 ectodermal cells sequentially and transiently express gcm
. From each patch, a single large blast cell delaminates and maintains gcm
expression. These are tentatively identified as the peripheral glioblast and the longitudinal glioblast. By late stage 11, all of the progeny of these glioblasts as well as additional glial cells express gcm
. Glial expression is gone by stage 15. In the brain lobes, gcm
is expressed in a complex pattern through stage 17. In the PNS, gcm
is transiently expressed in all repo
-positive glia along peripheral axon pathways and associated with sensory organs.