Expression of calbindin and calretinin in the human ganglionic eminence

The conspicuous ganglionic eminence representing a part of the telencephalic proliferative zone contains neuroblasts of the striatum. Recently it has been found to contribute significantly to the class of interneurons in the cerebral cortex. Subpopulations of cortical interneurons contain calretinin and calbindin. The expression of calretinin and calbindin in the ganglionic eminence and adjacent areas has been investigated immunocytochemically during fetal development using the brains of 10 infants ranging in age from 16 and 26 weeks gestation. Between 16 and 20 weeks gestation, numerous calretinin-immunreactive nerve cells are found in the ganglionic eminence, particularly in the mantle and the intermediate zones. The number of calretinin-immunoreactive cells decreases gradually from 21 weeks gestation onwards. Larger calbindin-immunoreactive cells are seen in the ganglionic eminence, and their number increases from 20 weeks gestation in the mantle zone. These results may indicate that calretinin-immunoreactive precursor cells, found in the ganglionic eminence, tangentially migrate toward the cortex. Moreover, the mantle zone displaying a specific calretinin and calbindin immunolabeling may represent an intermediate target for outgrowing axons. The findings are discussed with regard to central nervous system complications in preterm infants involving the ganglionic eminence.