Journal of Neuroscience, Vol 2, 1494-1498, Copyright © 1982 by Society for Neuroscience
Cerebellar Purkinje cells are descended from a small number of progenitors committed during early development: quantitative analysis of lurcher chimeric mice
R Wetts and K Herrup
Previous analysis of lurcher in equilibrium wild type aggregation chimeras
revealed that the degeneration of cerebellar Purkinje cells (PCs) in
lurcher mutants is due to a defect intrinsic to the PCs themselves. Thus,
all of the PCs remaining in lurcher chimeric mice are descended from only
the wild type embryo. In this study, we have determined the number of PCs
in four lurcher chimeras and three wild type mice. The low number of wild
type PCs (10,200) in half of the cerebellum of one chimera (chi 11)
suggested that these cells might be descended from a single progenitor.
This idea is strongly supported by the quantitative analysis of the PCs in
the other animals. These numbers are integral multiples of the number of
PCs in chi 11. We believe that each stepwise increase in the number of PCs
in the chimeras is due to the addition of a single wild type cell to the
progenitor pool. The existence of integral multiples implies that no other
cells can contribute to the PC population after the progenitors become
committed to forming PCs. We cannot know, however, whether the PC
progenitors also give rise to other cell populations. The values of the
integrals in wild type mice indicate that the entire PC population descends
from a small number of progenitors (8 in C3H/HeJ mice). We calculate that
these progenitors are committed during the neural plate to neural fold
stage of development. Thus, the fate of the progenitors of the cerebellar
PCs is restricted very early in neural development.
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