Gs. Boyan et al., ORGANIZATION OF A MIDLINE PROLIFERATIVE CLUSTER IN THE EMBRYONIC BRAIN OF THE GRASSHOPPER, Roux's archives of developmental biology, 205(1-2), 1995, pp. 45-53
We have studied a group of midline cells in the embryonic brain of the
grasshopper by using immunocytochemical and intracellular dye injecti
on techniques. This cluster of midline cells differentiates between th
e pars intercerebralis lobes of the protocerebrum during early embryog
enesis, and is composed of putative midline progenitors as well as neu
ronal and glial cells. Annulin immunoreactive glial processes surround
the borders of the midline cell cluster and also form a network of pr
ocesses extending from there to the borders of proliferative clusters
in the brain hemispheres. Among the cells that derive from the midline
cluster are two bilaterally symmetrical pairs of identified primary c
ommissure pioneer neurons. By navigating along the glial-bound borders
of the midline proliferative cluster, the axons of these pioneers est
ablish an initial axonal bridge across the brain midline. This analysi
s identifies a glial-bound midline proliferative cluster in the brain
and shows that neuronal and glial cells of this cluster are closely as
sociated with neurons pioneering the primary brain commissure. Compara
ble features of midline cells in the ventral ganglia and similarities
to other proliferative clusters in the brain hemispheres are discussed
.