The white matter in adult CNS

The white matter in adult CNS (in regard to developing neural tube) is formed from the 

A. Ventricular zone 
B. Marginal zone 
C. Ependymal zone 
D. Intermediate zone

Answer. B. Marginal zone

·   The white matter of the adult CNS is derived from the marginal zone of the developing neural tube

·   The other layers of the neural tube are the mantle zone, which forms the gray matter, and the ventricular zone from which astrocytes, oligodendrocytes, and neurons differentiate.

1. The first stage of neural tube development involves cell proliferation and occurs before neural tube closure.

2. The second stage involves the differentiation of neurons from the germinal (ventricular) layer of the epithelium and is initiated after closure of the neural tube. Differentiation of three distinct layers of the wall is observed. Mitotic activity occurs in the ventricular zone, closest to the lumen.

3. The next zone is the mantle (intermediate) zone, where cell bodies of differentiating motor neurons are located. The most peripheral zone is the marginal zone, which contains the myelinated axons of the developing motor neurons (adult white matter).