Tracing Neuroepithelial Cells of the Mesencephalic and Metencephalic Alar Plates During Cerebellar Ontogeny in Quail – chick Chimaeras

Abstract

The quail-chick chimaera system was used to investigate the origin of the various neuronal cell types of the cerebellum from the mesencephalic and metencephalic brain vesicles at the 11- to 14-somite stage in the avian embryo. We have already demonstrated that the cerebellum is derived from both the mesencephalic and metencephalic brain vesicles. The mesencephalic contribution to the cerebellum is restricted to a mediodorsal territory inserted as a V-shaped area into the primitive metencephalic vesicle through complex morphogenetic movements taking place from day 2 to day 4 of embryonic development. Here we report that the cerebellar presumptive territory extends along the anteroposterior axis, over the caudal half of the mesencephalon and the rostral half of the metencephalon. Along the dorsoventral axis, the cerebellar anlage is located in the alar plates at the exclusion of the roof and basal plates, i.e. lies in the lateral walls of the neuroepithelium in the area included between approximately 25 and 120 degrees with respect to the sagittal plane. We also report that the neuroepithelium corresponding to the cerebellar presumptive territory also yields other brain structures (e.g. part of the optic tectum in the mesencephalon). The external granular layer (EGL) arises only from the rostral metencephalon, undergoing extensive tangential movements which we have analysed in detail: the more ventral the position of cells in the metencephalic alar plates the more rostral and lateral is their position in the EGL. Finally, we discuss the fact that the cerebellar cortex, an integrative structure of the brain, arises from the alar plates of the neural tube. This is consistent with the general spatial organization of the neural anlage of the vertebrate embryo, in which this part of the neuroepithelium is devoted to the production of interneurons, whereas the basal plate and the neural folds yield motor structures and primary sensory neurons respectively.

Genetic inducible fate mapping in mouse: Establishing genetic lineages and defining genetic neuroanatomy in the nervous system

“…2D; Sgaier et al, 2005). In this way, GIFM delineated morphogenetic movements that had been suggested from transplantation studies in chick and random genetic marking of clones in mouse (Hallonet and Le Douarin, 1993;Alvarez Otero et al, 1996;Mathis et al, 1997). In additional experiments, distinct mediallateral regions of the cerebellar primordium at E12.5 were marked and their fate determined by inducing marking at different time points using two En-CreER lines (Sgaier et al, 2005).…”

Cerebellar granule cell precursors can differentiate into astroglial cells

“…Recent studies, however, using quail-chick chimeras (28,29), transplantation of EGL cells (30), or retroviral labeling of EGL cells (31,32) indicate that cells in the EGL give rise to granule cells exclusively in vivo. Here, we show that some EGL GCPs can differentiate into GFAP-positive glial cells in vitro also.…”

Besides Purkinje cells and granule neurons: an appraisal of the cell biology of the interneurons of the cerebellar cortex

“…Indirectly, this suggested the notion that the lineages of these cell types are well separated, in space, and presumably also in developmental potential. Although a series of earlier observations had put this view in question (prominent among them (Napieralski and Eisenman 1993;Hallonet and Le Douarin 1993) the view that all inhibitory cortical interneurons derive from a precursor population-and maybe even a common precursor-that reaches its Wnal destinations by migrating through the deep cerebellar mass and nascent white matter gained broader attention and general acceptance following the reports by Zhang and Goldman (1996a, b) that inhibitory interneuronal precursors could be marked by injecting a retroviral marker into the deep parts of the cerebellar anlage. These studies also implied that precursors in this location (i.e., which had left the ventricular zone) were dividing, and they also raised the issue of a potential lineage relationship between inhibitory interneuronal precursors and other cells marked, notably glial cells (see also Mathis et al 1997).…”