Fig. 1. Combinatorial expression of MASH1, DLX2 and markers of proliferation and
differentiation provide evidence for distinct stages of cellular maturation in
the lateral ganglionic eminence (LGE). Fluorescence microscopic images of
wild-type subcortical cells stained with a pair of antibodies (differentially
labeled with green or red fluorophors) that bind to the proteins indicated
above each panel; yellow cells are double labeled. Coronal sections (10 µm)
from E10.5 embryos (A-D) and E11.5 embryos (F-J) show the primordium of the
LGE. (E) Dissociated cells prepared from E10.5 subcortical telencephalon
(arrows indicate double-positive cells). The boxed areas in
Fig. 2 show the approximate
regions of the LGE shown in Fig. 1. PCNA labels proliferating cells, and
thereby defines the location of the progenitor zones, whereas MAP2 and GABA
label postmitotic neurons (arrow in C,D), and thereby define the position of
the mantle zones. PH3 labels M-phase cells in the VZ and the SVZ (arrow in H).
P1 progenitors (MASH1-/DLX2-) and P2 progenitors (P2, MASH1+/DLX2-) are only
in the VZ. P3 progenitors (MASH1+/DLX2+) are in the VZ and SVZ. In A, P1
progenitors are unlabeled, P2 progenitors are green and P3 progenitors are
yellow. N1 cells are the earliest born neurons; we propose that they are
generated from P2 progenitors (see Fig.
7). N1 neurons are MAP2+ and continue to express DLX2 (see inset
in D). The LGE progenitor zone can be divided into at least two parts along
the dorsoventral axis: the dorsal LGE (dLGE) and the ventral LGE (vLGE) (Yun
et al., 2001). dLGE neurogenesis precedes that of vLGE, and therefore may
contribute to a major portion of the N1 population. Some MASH-/DLX2+ cells are
observed in the VZ and SVZ (particularly in the dLGE); these are the red cells
in the VZ in A. These cells might correspond to another type of progenitor.
LV, lateral ventricle; ME, mesenchyme; MZ, mantle zone; VZ, ventricular zone;
SVZ, subventricular zone. Scale bars: 100 µm. Arrows in J indicate examples
of PCNA/Mash1 double-positive cells.