Glial differentiation in the germinal layer of fetal and preterm infant brain: an immunocytochemical study.

The germinal layer in preterm infants is a common site of intracerebral hemorrhage that is associated with increased mortality and morbidity in survivors. This matrix is composed of a mass of immature cells containing many thin-walled blood vessels. A major factor in the occurrence of hemorrhage at this site is the absence of a network of fibers to support these vessels. This immunocytochemical study has examined glial differentiation within the germinal layer of brains from fetuses and preterm infants of gestational ages 18 to 35 weeks. Progressive glial differentiation with gestation is described. This process is not uniform and the more posterior germinal layer, lying over the body of the caudate nucleus, demonstrates more rapid maturation than that lying anteriorly near the head of the caudate nucleus. Anteriorly, even at 35 weeks of gestation, a central core of germinal layer cells remains immature with little evidence of glial differentiation. These changes may be related to the occurrence and distribution of germinal layer hemorrhages in preterm infants of varying gestations.