Diversity of radial glial cells is formed along the dorso-ventral axis in the developing mouse spinal cord.

The central nervous system (CNS) of the mammalian embryo is organized according to the expression of region-specific transcription factors along the anterior-posterior (A/P) and/or dorso-ventral (D/V) axis. For example, the dorsal ventricular zone (VZ) of the embryonic spinal cord expresses Pax3 and Pax7, the ventral VZ expresses Pax6, and the more ventral VZ expresses Nkx2.2. Properties of neuronal precursors located in the VZ are determined by the characteristic expression patterns of these transcription factors, leading to the generation of distinct classes of neurons. Recent studies demonstrated that radial glial cells produce neurons in addition to glia during CNS development. Thus, neuronal precursor diversity may reflect the diversity of radial glial cells. If the radial glial cells show diversity, astrocytes generated from them may also. To investigate this hypothesis, we analyzed the expression of radial glial cell markers and transcription factors in the mouse embryonic spinal cord. I show that radial glial cells vary in expression of the astrocyte-specific glutamate transporter(GLAST) and the brain-lipid-binding protein (BLBP) at embryonic day 12.5(E12.5). The region where GLAST is strongly expressed in the ventral radial glial cells is closely related to the Pax6-expressing domain, and the weakly expressed region corresponding to the Nkx2.2-expressing domain. Furthermore, dorsal radial fibers expressed ephrin-B1, where GLAST expression is negative. Thus, different types of radial glial cells exist according to the transcription factors at E12.5. Since GLAST is considered to be expressed when radial glial cells aregenerating astrocytes, there may also be diversity in glial precursor cells along the D/V axis in the mouse spinal cord