El-Magd, M.A., Saleh, A.A., Farrag, F., Abd El-Aziz, R.M., Ali, H.A. and Salama, M.F
الملخص العربي
This study was conducted to identify the regulation of the
expression of the cEbf1–3 (chick early B-cell factor 1–3) genes
in the pharyngeal arches (PAs), cranial sensory ganglia and
placodes. cEbf1 and cEbf3 were mainly expressed in the cranial
neural crest cells (NCCs) occupying the PAs, but cEbf2
was expressed in the mesenchymal core. cEbf1–3 were
prominently expressed in the olfactory placodes, but cEbf1
and cEbf3 were only expressed in the otic vesicle. cEbf1 was
expressed in all cranial sensory ganglia, cEbf2 (only) in the
dorsolateral ganglia and cEbf3 in the trigeminal and vestibular
ganglia. The removal of the source (the cranial neural
tube) of the cranial NCCs before their migration to the PAs
led to downregulation of cEbf1 and cEbf3 and upregulation
of cEbf2 expression. Gain- and loss-of-function experiments
showed that sonic hedgehog did not regulate cEbf1–3 expression
in the PAs or associated ganglia. Bone morphogenetic
protein 2 (Bmp2) can, however, directly and indirectly regulate cEbf1 and cEbf3 expression in the PAs and the proximal
(NCC-derived) portion, but not the distal (placodal-derived)
portion of the cranial sensory ganglia. Conversely,
cEbf2 expression was upregulated following injection of
Noggin before the migration of NCCs, but did not change
after the overexpression of either Noggin or Bmp2 in the
arch after NCC migration. In conclusion, Bmp2 regulates
cEbf1 and cEbf3 expression in PAs and cranial sensory ganglia
both directly and indirectly, via the migration of cranial
NCCs. However, cEbf2 expression in the mesenchymal core
of PAs is controlled by other undetermined signals.
محمد رزق ابو المجد الغنام | Mohammed Rizk Abu El-Magd El-Ghannam | 8888