Figure 7.

Schematic representation of possible lineage relationships between neurons and oligodendrocytes linked via Olig transcription factors in human CNS development, based on our results (Jakovcevski and Zecevic, 2005b). (A) In the embryonic forebrain Olig1 and Olig2 appear to be expressed by separate progenitor cell pools, and our evidence suggests that Olig2⁺ progenitors give rise to neurons. Later during fetal development early oligodendrocyte progenitors express both Olig1 and Olig2, but mature MBP⁺ oligodendrocytes in the fetal forebrain are Olig1⁻/Olig2⁺. (B) In the embryonic human spinal cord we detected only Olig2 expression. At the later age (15 gw) Olig1 is expressed in early oligodendrocyte progenitors, whereas Olig2 is expressed in MBP⁺ oligodendrocytes. Interestingly, Olig2 was expressed in many NeuN⁺ postmitotic neurons in the dorsal, but not ventral horn.